Q&A with Dr. Sheri Colberg: Part 2

I recently gave a webinar for the American College of Sports Medicine (and Technogym) that reached almost 1,200 participants in real time. You can watch the webinar, titled “The Role of Physical Activity in Type 2 Diabetes Management and Prevention,” posted on Youtube.

While the Q&A portion was done live, it was not included in the webinar recording. Plus, there were many additional questions for which there was no time to discuss. This article addresses the second half of those questions (the rest were answered in November 2021).

Q: Please mention blood sugar level prior to as well as fluid and hydration intake prior to ANY exercise is crucial to predict glycemic response…. regular blood glucose checks are key until you know how they respond.

A: The guidelines are that you should not begin exercise with a blood glucose >250 mg/dL (13.9 mmol/L) with moderate or high levels of blood or urinary ketones. If you don’t usually test for ketones, just make sure you have enough insulin “on board” to counterbalance the glucose-raising hormones that get released during physical activity. The harder the exercise is, the more of these hormones get released.

The guidelines also suggest that people should use caution during activities when starting with a blood glucose >300 mg/ dL (16.7 mmol/L) without excessive ketones, stay hydrated, and only begin if feeling well. For instance, if you take insulin and just ate a big meal, exercising right after when you may be experiencing a spike is usually okay because you have enough insulin in your body to bring the glucose levels down with activity.

As for hydration, drink adequate fluids before, during, and after exercise, as well as avoid exercising during the peak heat of the day or in direct sunlight to prevent overheating. These precautions are particularly important when someone has been experiencing hyperglycemia (elevated blood glucose levels) that can lead to dehydration or if someone has autonomic (central) nerve damage that can impair normal heat dissipation during exercise.

Q: What are your recommendations for glucose testing before, after or during exercise?

A: It really depends on the individual. Adults with type 2 diabetes not taking insulin or sulfonylurea oral medications may not need to check because their blood glucose is unlikely to drop too low during activities—but they may want to check to be motivated by its ability to lower blood glucose, especially during post-meal spikes.

If you use insulin, it is important to check before, occasionally during, and even at varying intervals of time after activities to prevent both lows and highs and to treat them more quickly. Frequent monitoring also helps with establishing usual patterns, trends, and responses that make it easier to predict what insulin regimen or food changes may be needed to keep blood glucose levels balanced, especially you may be prone to developing late-onset hypoglycemia following an activity that is particularly long or intense. 

Q: In order to avoid exercise-induced hypoglycemia, what are the normal values of glucose monitoring before starting exercise? Is there a target glycemic range that you would recommend for those with Type 1 diabetes to begin exercise to prevent hypo during activity? Also, how can people recognize and respond to hypoglycemic reactions?

A: A good starting blood glucose level can vary with the activity, time of day, and normal responses. Most people like to start in the range of 70 to 180 mg/dL (3.9 to 10.0 mmol/L), but it really depends. For example, if you’re going to do early morning exercise (before insulin or food), your blood glucose may raise due to the higher levels of insulin resistance at that time of day. Many people actually choose to exercise then so that their risk of going low is minimal. However, others prefer to exercise with slightly more insulin on board (but not too much) later in the day to avoid exercise-related highs, especially when doing more intense workouts. Some people actually give small amounts of insulin prior to doing intense early morning workouts to prevent going too high.

As for hypoglycemia, it can have a variety of symptoms, including shakiness, visual spots, lethargy, extreme fatigue, and more. To make it more challenging, the symptoms can vary by the person and by the activity or time of day. Learn to recognize your own symptoms by confirming your blood glucose levels whenever any symptoms arise. Anything with glucose works fastest to treat a low, but you can use a variety of carbohydrate sources and follow up with snacks with a balance of carbs, protein, and fat if lows tend to persist or recur over time.

Q: What resources would you recommend for additional information regarding clinical exercise programming with respect to common diabetes medications?

A: There are two position/consensus statements with compiled information about being physically active with diabetes that would particularly useful when it comes to diabetes medications and their impact on physical activity. One is an American Diabetes Association position statement from 2016 (PMID: 27926890), and the other is a consensus statement on type 1 diabetes from 2017 (PMID: 28126459).

Particularly for anyone using insulin or taking sulfonylureas (and possibly meglitinides within 2-3 hours of physical activity), it is important to carry rapid-acting carbohydrate sources during activities to treat hypoglycemia and have glucagon available to treat severe hypoglycemia (if you are prone to developing it).

Q: Diabetes type 2 has been related to intramyocellular lipid accumulation. As fat oxidation is optimized at a low exercise intensity, would you recommend low exercise intensity over high intensity exercise for patients with diabetes?

A: No. Any intensity of exercise that someone with type 2 diabetes can do is fine. While it is true that slightly more fat is used during lower intensities compared to higher ones, the primary fuel used by the body during most moderate or higher-intensity work is carbohydrate. Fat is the primary fuel during all recovery periods. Intramyocellular lipids, therefore, are the primary fuel used during periods of rest, which is most of the time. Just try to maximize your total calorie expenditure from physical activity without worrying about exercise intensity. (In other words, completely ignore anything that tells you that you are in a “fat burning range” as it is incorrect and irrelevant.)

Q: What precautions need to be taken if there is peripheral neuropathy?

A: It is generally recommended that people with moderate to severe peripheral neuropathy (loss of sensation in the feet) limit or avoid activities that may cause foot trauma, such as prolonged hiking, jogging, or walking on uneven surfaces. For them, it may be more appropriate to engage in non-weight-bearing exercises (e.g., cycling, chair exercises, swimming); however, they should avoid aquatic exercise with unhealed plantar surface (bottom of the foot) ulcers. It is also important to check feet daily for signs of trauma and redness. Other precautions include choosing shoes and socks carefully for proper fit and wearing socks that keep feet dry, such as some of the newer athletic socks that are polyester-cotton blends. Finally, neuropathy can affect both gait and balance, so they should avoid activities requiring excessive balance ability.

Q: I work with many folks who have kidney failure due to diabetes. Are there any precautions even though the client has been medically cleared?

A: Yes, the main precautions for these individuals revolve around avoiding exercise that causes excessive increases in blood pressure, such as heavy weight lifting, high-intensity aerobic exercise, and anything that causes breath-holding. For most, high blood pressure is common, and lower intensity exercise may be necessary to manage blood pressure responses and fatigue. The good news is that light to moderate exercise is possible during dialysis treatments if electrolytes are managed properly. A recent study showed that people on dialysis can safely engage in aerobic, resistance, or combined training with good outcomes on fitness, blood pressure, and metabolic function (PMID: 31865607).

Q: One of the complications you mentioned was peripheral arterial disease. The exercise pattern is less in these individuals. What do you think in that aspect when we can’t do higher intensity exercise what pattern should we focus?

A: Peripheral artery disease occurs when significant amounts of plaque are present in the blood vessels supplying the legs and feet. This blockage can cause pain and leg cramps, particularly during harder exercise, due to a reduced circulation and supply of blood and oxygen to those peripheral areas. While it may appear that exercise makes things worse, given the pain often associated with it, the opposite is true. It can actually improve circulation with formation of new, collateral blood vessels.

In general, the intensity of activity mainly impacts the recruitment of additional muscle fibers, specifically faster twitch fibers that are more anaerobic in nature than aerobic. Although fitness gains may be lesser with lower-intensity activities, doing anything at a low or moderate intensity still confers many health benefits, including increasing blood flow to areas with some artery blockage and enhancing oxygen consumption in engaged muscles (PMID: 28385410). Doing activities at any intensity that is possible, therefore, should be encouraged, and walking is fine for most people to engage. People should be encouraged to try alternate activities when pain in their legs is more severe or intolerable during a given activity. 

Q: Which fitness trackers monitor blood glucose levels and how does this work?

A: If discussing only FDA-approved glucose monitors, at the current time a person has to wear a separate continuous glucose monitoring (CGM) device like the latest ones from Dexcom that can transmit its readings to a fitness monitor, such as select Apple or Fitbit smartwatches, or to apps like the one associated with Fitbit or other trackers. A compatible smartphone is required to display data on an Apple Watch, and the Freestyle Libre CGMs work through a linked phone app as well. This connectivity is currently being updated and enhanced, so check the latest devices for specifics on which ones connect and how to set them up.

Q: Do you have any apps you recommend to track exercise?

A: There are so many different apps, and most of the latest smartphones have accelerometers in them that can track steps or distances traveled. I use one called “Map My Walk” that tracks most types of activity (not just walks) and gives distance, time, and more. Many others also estimate calorie use. It really depends on what data sets are most important to you.

Check back last month for Part 1 of this webinar-related Q&A!

Q&A with Dr. Sheri Colberg: Part 1

I recently gave a webinar for the American College of Sports Medicine (and Tcchnogym) that reached almost 1,200 participants in real time. You can watch the webinar, titled “The Role of Physical Activity in Type 2 Diabetes Management and Prevention,” posted on Youtube.

While the Q&A portion was done live, it was not included in the webinar recording. Plus, there were many additional questions for which there was no time to discuss. This article addresses the first half of those questions, and the rest will be answered in early December 2021.

Q: Can you speak to the ability or inability to “cure” T2D? Does it have to do with the loss of the pancreatic beta cells?

A: Yes, it has generally been shown that new-onset type 2 diabetes is easier to “reverse,” meaning that blood glucose levels can be so well managed that it appears diabetes has been cured. Over time, a loss of some insulin-making capacity occurs in people with long-standing T2D, particularly if it has not been well-managed, related both to the impairment of pancreatic β-cell function and the decrease in β-cell mass. (PMID: 27615139)

Q: Isn’t insulin resistance now found to be in T1DM as well?

A: Yes, anyone can develop insulin resistance, and it occurs in at least a third of people with type 1 diabetes as well, although it is not always associated with excess weight gain or overweight. Since people with T1D lack insulin due to the body’s own immune system killing off the pancreatic β-cells, greater resistance increases the total doses of insulin needed (whether injected, pumped, or inhaled). Thus, they have developed characteristics of both types and have “double diabetes.” (PMID: 34530819)

Q: Under lifestyle goals, would you include stress management?

A: Stress management was not assessed in the large multi-center clinical trials on type 2 diabetes prevention, but mental stress can certainly raise blood glucose levels due to the greater release of glucose-raising hormones like cortisol and adrenaline. It certainly would be beneficial to address better ways to manage mental stress as part of lifestyle goals for optimal blood glucose outcomes. (PMID: 29760788)

Q: As each person has their own limitations how important is it to get a physician clearance and exercise guidelines before working with the client?

A: It really depends on the person’s circumstances. How intense will the planned activities be? Is the person currently sedentary? Has he/she been getting annual checkups to monitor blood glucose management and to check the status of any complications? Does he/she have diabetes-related or other health complications that could be worsened by physical activity? The lower the intensity, the more active an individual has been, and the lower the risk for cardiovascular complications, the less likely medical clearance is absolutely necessary.

The latest ACSM Consensus Statement on activity and T2D will be released in early 2022 in Medicine & Science in Sports & Exercise and states, “For most individuals planning to participate in a low- to moderate-intensity physical activity like brisk walking, no pre-exercise medical evaluation is needed unless symptoms of cardiovascular disease or microvascular complications are present. In adults who are currently sedentary, medical clearance is recommended prior to participation in moderate- to high-intensity physical activity.”

Q: Can flexibility training be used for warmups, or do you recommend it only after the workout?

A: While it is possible to do flexibility training at any point during a workout, joints tend to have a greater range of motion after blood flow to those areas has been increased with a light or short aerobic warmup. It may be prudent to do a quick aerobic warmup, some stretching, the full workout, and then more extensive stretching afterwards for optimal results.

Q: Was there any particular protocol for strength training? sets, reps, periodization? What is considered “intense” resistance work? Would fatigue based off of several sets of moderate intensity be recommended then?

A: That is a tough question, and it depends on who you ask. I have seen a lot of debate over the optimal strength training protocol during the many years I have been in the exercise/fitness world. If people are just starting out with resistance training, they will gain from doing even a minimal amount of training.

Starting out with 1-3 sets of 8 to 10 main exercises that work all of the large muscles groups at a light to moderate intensity is considered appropriate for most older or sedentary adults, many of whom have joint limitations or health issues. Moderate intensity is considered 50%-69% of 1-RM (1 repetition maximum) and vigorous is 70%-85% of 1-RM. Both intensity (fewer reps at a higher intensity) and the number of sets (3-5) or days of training (starting at 2, progressing to 3 nonconsecutive days) can increase over 2 to 3 months. Periodization is usually not undertaken by older adults, but may be appropriate for younger, fitter ones.

Q: Do you have any insight or are aware of any studies that involve high intensity (%1-RM) resistance training and T2DM? Or any studies that compare resistance training volume (Sets x Reps x Load)?

A: Some older studies have determined that glycemic management is improved by supervised high-intensity resistance training in people with type 2 diabetes (PMID 12351469). Others have also found that home-based (and, therefore, unsupervised) resistance training results in a lesser impact on blood glucose levels, likely due to reductions in adherence and exercise training volume and intensity (PMID 15616225).

Q: I’m still confused about glucose response to acute exercise. Which is better if you want to bring down your BG right now? Can you speak to the possibility of increased blood sugars with intense aerobic exercise?

A: Most light-to moderate-intensity aerobic exercise will lower blood glucose levels, assuming that some insulin is present in the body. (People who are very insulin deficient may have a rise in blood glucose from doing any activity.) Any activity that gets up into the intense/vigorous range, even if only during occasional intervals, has the potential to raise blood glucose due to a greater release of glucose-raising hormones during the activity. This is particularly true if the activity is short and intense. In individuals with any type of diabetes, declines in blood glucose during high-intensity interval exercise are smaller than those observed during aerobic exercise.

That said, if someone wants to lower blood glucose right now with exercise, it also depends on the timing of exercise. Doing something light to moderate for at least 10 to 30 minutes is the best bet, particularly after a meal when insulin levels are generally higher. Avoid doing intense aerobic or heavy resistance training as those may have the opposite effect. For early morning exercise, any intensity can potentially raise blood glucose due to higher levels of insulin resistance then and lower circulating levels of insulin in the body.

Q: I had an endocrinologist say that long runs or walks are better, and another one said to do a bit of weights.

A: Which activities someone chooses to do should depend on the goal of the training. Is it increased fitness, lowering blood glucose levels acutely, or gaining strength and improving overall blood glucose management? Long, slow aerobic training does have the benefit of increasing cardiorespiratory fitness and lowering blood glucose levels (in most cases). Resistance training, on the other hand, increases muscular strength and endurance and helps people gain and preserve muscle mass, which is where most carbohydrates are stored in the body. It may not, however, lower blood glucose levels, at least not acutely.

Both have their place in a weekly training regimen. Insulin resistance is lowered for 2 to 72 hours following a bout of aerobic training. Resistance training has more of a long-term impact on insulin action by enhancing carbohydrate storage capacity. The best advice is to do some aerobic training at least every other day and some resistance training at least 2, and preferably 3, nonconsecutive days per week. These activities can be done on the same days or different ones.

Tune in for Part 2 of this webinar-related Q&A coming soon!

Can You Slow or Reverse Aging with Physical Activity?

In the recent past, we discussed how to know if joint problems (e.g., overuse injuries) are due to being active, aging, or diabetes, but let’s just focus on aging by itself this time around. We’d all love to slow down normal aging or even reverse some aspects of it, but is that even possible?

There is a normal decline in most of our physiological systems that starts at around the age of 25 and continues over time. Although some of the bodily changes people experience over time are due to normal aging, many are actually caused by either disuse or a disease state. What we can mainly accomplish with physical activity is not to stop the decline totally but rather to slow down how quickly it happens (that is, its downward trajectory).

For example, bone density decreases slowly over time but extended bedrest, a sedentary lifestyle, and weightless environments (like being on the space station) all speed up bone mineral losses. Your goal should be to slow the rate of decline with physical activity, dietary improvements, and possibly medications to keep your bones from reaching a critical fracture point before you reach the end of your natural life span.

In many areas of your body, you can slow aging or possibly reverse premature aging with physical activity. The main areas you can impact include:

  • Heart: Despite people jokingly saying they have a finite number of heart beats so exercise is to be avoided, the reverse is actually true. We may have a finite number of beats, but regular physical activity likely increases that number. Interestingly, the heart is one of the few muscles in the body constantly exercises, and it requires an adequate blood supply to fuel its contractions. Exercise training can increase the diameter of coronary arteries and blood flow to the heart muscle, even if you have some blockage in your coronary arteries. Resistance training in particular appears to increase coronary blood flow and is recommended even in people who have diagnosed coronary artery disease.
  • Bones: Make sure to include both weight-bearing or bone “stressing” activities, if possible, to stimulate deposition of bone minerals and slow losses over time. Bearing weight on your bones creates stress that stimulates bones to grow stronger, as does the pulling of tendons on attached bones when muscles contract. Good activities include walking and other weight-bearing activities, resistance training (upper and lower body), and even whole-body vibration training in many cases.
  • Joints: Resistance exercises targeting the muscles around joints with osteoarthritis can lessen joint pain by taking some of the stress off the joint surfaces, tendons, and ligaments. Include both flexibility and resistance exercises to keep joints more limber, surrounding muscles strong, and mobility enhanced. Strengthening muscles around replacement joints is also crucial for long-term success with those new joints.
  • Core muscles: As part of the body core, abdominal, lower back and lower body muscles are critical for standing and balancing. Use targeted resistance exercises to build and retain their muscle mass. Also, practice balance and agility exercises to improve balance ability and prevent falls. In older adults, working on functional fitness is important for building strength and maintaining flexibility for basic self-care and independent living.
  • Ankle muscles: The ankles are complex joints and many problems arise when weak muscles allow them to roll too far in or out. Work on keeping your ankles strong to keep your balance, avoid falls, and prevent foot bone fractures and inflammation of tendons around the ankles. Include a series of ankle-strengthening exercises in your weekly routine, and work on keeping ankle flexibility to avoid injuries and falls.
  • Eye muscles: Most people over the age of 50 need longer arms (to hold things away from their eyes to read them). Instead of getting reading glasses or bifocals, try some eye exercises to retain the strength and mobility of the eye muscles responsible for near-focus reading and distance vision. These include simple exercises like rotating the eyes in various directions and alternating between focusing on near and far, back and forth.
  • Pelvic floor muscles: As mentioned in a prior article, pelvic floor muscles (or Kegel exercises) can keep those muscles strong and help prevent bladder leakage and urinary stress incontinence common with aging. A beneficial side-effect of doing Kegel exercises is greater sexual enjoyment, so why not give these a try? For starters, practice stopping your urine in mid-flow and then releasing it.
  • Brain: Physical activity helps slow the rate of brain decline (both cognitive ability and memory) by ensuring adequate blood flow to the brain and stimulating various areas involved in voluntary movement. Try doing simple memory exercises (like memorizing lists and repeating them later) as well as regular physical activity to keep your brain in top form and lower your risk for dementia. Better yet, do memory exercises while exercising for the best results.

However, the slow decline of the nervous system over time—as seen in slower reaction times—is not preventable. The best things you can do for your nerve function is to eat plenty of healthy foods replete with essential vitamins, minerals, and phytonutrients and continue to be regularly active to slow the decline of everything else.

Physical activity is truly one of the best tools we have to improve the quality of our lives as we age and prevent declines from disuse and diseases related to poor lifestyles, regardless of how long we live. Here’s to using exercise to make it to 100 and beyond—with faculty intact and bodies (almost) fully functional!

How Glucagon Impacts Type 1 Diabetes and Vice Versa

Glucagon is such an important hormone when it comes to blood glucose management in everyone—and it both impacts and is impacted by type 1 diabetes (T1D). A recent mini-review in Physiological Reports (1) focused on altered glucagon responses brought up some interesting points that are worth discussing further.

We have known for a while that people with T1D have blunted or absent glucagon release when their blood glucose levels drop too low (2, 3). The five glucose-raising hormones—of which glucagon is one—are released and regulated by a variety of metabolic stressors like fasting, exercise, anxiety, illness, and more. In adults with T1D, even a single prior hypoglycemic event or a workout can blunt the hormonal response (including glucagon, epinephrine, and more) to the next low the same day or the next (4-6). Even in adults without diabetes, several bouts of hypoglycemia can impact the hormonal responses to the next low somewhat; however, their glucagon release is normal (7). So, why is glucagon so impacted by T1D and how?

In answering this, let’s revisit the main points of the recent mini-review (1):

  • The regulation of pancreatic alpha cells leading to the release of glucagon is complex and may involve several feedback loops (where the rise and fall of things can interplay).
  • Glucagon secretion from alpha cells is regulated by amino acids (the building blocks of protein), glucose (directly and/or indirectly), the central (autonomic) nervous system, incretins (gut hormones released into the blood after eating that stimulate insulin release), and signaling from beta and delta cells in the pancreas.
  • During hypoglycemia, glucagon signals the liver to release glucose, which is does either by breaking down glycogen or creating new glucose from precursors (like amino acids).
  • Pancreatic alpha cells are less responsive to changes in blood glucose than they are to certain amino acids; ones like alanine can cause a greater release of glucagon.
  • Glucagon release during hypoglycemia is absent in individuals with T1D, but it still responds to many other stimuli including fasting, physical and mental stress, and exercise, all of which may rely on different mechanisms to release glucagon.
  • Whatever is causing the absent glucagon secretion in T1D in response to hypoglycemia appears to reside within the pancreatic islets (of Langerhans) themselves.
  • Abnormal glucagon secretion is not confined to hypoglycemia as individuals with T1D secrete extra glucagon after meals, which can contribute to insulin resistance.

As I discussed in a recent blog, part of why glucagon release is altered in T1D is the lack of insulin in the circulation around the liver when insulin has to be delivered under the skin or inhaled. Functioning beta cells normally make insulin while the alpha cells of the pancreas make glucagon, but T1D removes the insulin release, thus altering the one typical check and balance on glucagon. Both a lesser storage of glycogen in the liver and an excess release of glucose after meals and overnight is the result.

However, as the mini-review reveals, the interactions and feedback loops are potentially a lot more complicated than that. Even youth with T1D have impaired plasma glucagon responses to hypoglycemia during their first year after diabetes onset, and older individuals with T1D still making a little of their own insulin also have defective and absent glucagon responses to hypoglycemia (8). The mini-review also suggests that the absence of glucagon secretion after hypoglycemia is irreversible and specific to lows since other stimuli—including administration of amino acids, insulin withdrawal, exercise, and more—can cause glucagon release. Perhaps this is why doing some high-intensity (glucagon-releasing) exercise often raises blood glucose or can be used to manage blood glucose during activities (9, 10).

So, is there anything people can do to compensate for the lack of glucagon release during blood glucose lows? Maybe when glucose goes low, doing a short sprint can help. Also, consuming some amino acids (via protein) may improve their glucagon responses and how well they can think during lows (11). Some groups are working on creating mini-dosing with glucagon with a pen (like an insulin pen but with glucagon in it). Whatever the answer, it is abundantly clear that anyone with T1D needs a workaround to raise glucagon by other means to treat hypoglycemia until a cure for diabetes is found.

References:

  1. Bisgaard Bengtsen M, Møller N. Mini-review: Glucagon responses in type 1 diabetes – a matter of complexity. Physiol Rep. 2021;9(16):e15009. PMID: 34405569; https://doi.org/10.14814/phy2.15009
  2. Diabetes Research in Children Network Study G, Tsalikian E, Tamborlane W, Xing D, Becker DM, Mauras N, et al. Blunted counterregulatory hormone responses to hypoglycemia in young children and adolescents with well-controlled type 1 diabetes. Diabetes Care. 2009;32(11):1954-9. PMID: 19675205.
  3. Cryer PE. Hypoglycemia-associated autonomic failure in diabetes. Handb Clin Neurol. 2013;117:295-307. PMID: 24095133.
  4. Davis SN, Mann S, Galassetti P, Neill RA, Tate D, Ertl AC, et al. Effects of differing durations of antecedent hypoglycemia on counterregulatory responses to subsequent hypoglycemia in normal humans. Diabetes. 2000;49(11):1897-903. PMID: 11078457.
  5. Galassetti P, Tate D, Neill RA, Morrey S, Wasserman DH, Davis SN. Effect of antecedent hypoglycemia on counterregulatory responses to subsequent euglycemic exercise in type 1 diabetes. Diabetes. 2003;52(7):1761-9. PMID: 12829644.
  6. Sandoval DA, Guy DL, Richardson MA, Ertl AC, Davis SN. Acute, same-day effects of antecedent exercise on counterregulatory responses to subsequent hypoglycemia in type 1 diabetes mellitus. Am J Physiol Endocrinol Metab. 2006;290(6):E1331-8. PMID: 16449302.
  7. Moheet A, Kumar A, Eberly LE, Kim J, Roberts R, Seaquist ER. Hypoglycemia-associated autonomic failure in healthy humans: comparison of two vs three periods of hypoglycemia on hypoglycemia-induced counterregulatory and symptom response 5 days later. J Clin Endocrinol Metab. 2014;99(2):664-70. PMID: 24423306.
  8. Sherr J, Xing D, Ruedy KJ, Beck RW, Kollman C, Buckingham B, et al. Lack of association between residual insulin production and glucagon response to hypoglycemia in youth with short duration of type 1 diabetes. Diabetes Care. 2013;36(6):1470-6. PMID: 23288858.
  9. Bussau VA, Ferreira LD, Jones TW, Fournier PA. A 10-s sprint performed prior to moderate-intensity exercise prevents early post-exercise fall in glycaemia in individuals with type 1 diabetes. Diabetologia. 2007;50(9):1815-8. PMID: 17583795.
  10. Guelfi KJ, Ratnam N, Smythe GA, Jones TW, Fournier PA. Effect of intermittent high-intensity compared with continuous moderate exercise on glucose production and utilization in individuals with type 1 diabetes. Am J Physiol Endocrinol Metab. 2007;292(3):E865-70. PMID: 17339500.
  11. Rossetti P, Porcellati F, Busciantella Ricci N, Candeloro P, Cioli P, Nair KS, et al. Effect of oral amino acids on counterregulatory responses and cognitive function during insulin-induced hypoglycemia in nondiabetic and type 1 diabetic people. Diabetes. 2008;57(7):1905-17. PMID: 18390791.

Here We Go Again: The Low-Carb vs. High-Carb and Training Debate

Who knew I’d be talking about carbohydrate intake and being active for the third time this year, but here we go again! A lot of confusion still exists related to the practice known as “carb loading” as well.  Do you need to do it? Should you? How do you know?

This controversy keeps coming up because of all the low-carb diet followers out there, especially many people with diabetes. At the American Diabetes Association Scientific Sessions this year (held virtually in June 2021), the MOST popular session of the entire conference was the one I set up to debate low-carb and high-carb eating and athletics (discussed in Diabetes In Control in July) with a virtual meeting record of 3,300 views!

As I commented recently, this debate is still ongoing in active individuals without diabetes. However, some facts are irrefutable, and these can impact the decisions that you make about your dietary plan with diabetes:

  • During harder exercise, your active muscles rely almost exclusively on carbohydrate as a fuel. Carbs are converted into energy (ATP) more quickly and with less oxygen required than fat. Carbs acts like high-octane gas while other types give you less energy for the same amount of fuel (and supply it more slowly). You must use carbs to do hard exercise.
  • Your body can adapt to a lower carb intake and increase fat use during exercise, at least to a limited extent (see comment above). However, adapting takes weeks and your performance can be negatively impacted if you go low-carb without time to fully adapt.
  • While you are in the process of adapting, your training may suffer and you may feel bad during workouts. This may be why many athletes adopt a strategy of periodically doing endurance training with less carb intake but take in unrestricted carbs when competing (i.e., train low-carb and compete high-carb). Following this strategy may help you adapt faster compared to having a low- or a high-carb intake all the time (1).
  • Even if you do adapt to lower carbs during training, your body will not necessarily use fewer carbs when active. It may just shift downward the intensity at which you cross over from less carb to more fat use (2). This shift towards greater fat use occurs naturally whenever your muscles start to run out of stored glycogen; the rate of glycogen use appears largely unchanged by low-carb training, however.
  • No matter how you eat and train, for intense events sprinting and power lifting, a chronic low-carb intake may be detrimental to your performance if your muscle glycogen stores are low. On the other hand, for endurance activities, you can usually at least maintain how well you perform after adapting to low-carb eating, but chances are your performance may not be better (see first comment above).

When it comes down to it, instead of carb loading, simply varying your carb intake may be as beneficial to performance. For instance, you may want to endurance train with a lower carb intake to increase your ability to oxidize fat, but take in more carbs leading up to any events and during events to maximize your storage. People with diabetes just have to make sure that they are keeping their blood glucose levels in check during any high-carb intake.

If attempting to carb load for even a day (which is usually long enough if you rest or taper) and you take insulin, cover the carbs with enough rapid-acting insulin to keep your blood glucose as near normal as possible to maximize muscle glycogen storage. (Glucose cannot get into muscles cells during rest without insulin.) Most people take in plenty of carbs if they are eating enough overall and even as low as 40 percent of calories from carbs. Effective carb loading does not require you to eat a pasta dinner or massive amounts of starchy foods.

If you take any carbs in during exercise, which most people do during longer events and training even without diabetes, you’ll need very little insulin coverage (if any). If you limit your carb intake afterward, though, you may increase your chances of getting a nighttime low blood glucose, particularly if you use insulin (3). If you do not use insulin, you are unlikely to need any extra carbs during most shorter activities, regardless of how easy or hard you work out. Supplemental carbs are mainly for longer events (90 minutes plus) and for insulin users.

That said, anyone on a low-carb diet may benefit from supplementing with carbs as needed during endurance activities or training (1). Aim for a maximum of 75 grams per hour during prolonged or multi-day activities. During intermittent sports like hockey or soccer, 30 to 60 grams of carbs per hour may prevent fatigue or lows near the end of a game. Keep monitoring your blood glucose, though, as going too high or low can have negative effects on performance.

Primary reference: Colberg SR, Nutrition and exercise performance in adults with type 1 diabetes. Canadian Journal of Diabetes, 44(8):750-758, 2020 (https://doi.org/10.1016/j.jcjd.2020.05.014)

References:

1..  Impey SG, Hearris MA, Hammond KM, Bartlett JD, Louis J, Close GL, et al. Fuel for the Work Required: A Theoretical Framework for Carbohydrate Periodization and the Glycogen Threshold Hypothesis. Sports Medicine. 2018;48(5):1031-48. doi: 10.1007/s40279-018-0867-7. PubMed PMID: 29453741.

2.   Chang CK, Borer K, Lin PJ. Low-Carbohydrate-High-Fat Diet: Can it Help Exercise Performance? J Hum Kinet. 2017;56:81-92.(doi):10.1515/hukin-2017-0025.

3.   Scott SN, Anderson L, Morton JP, Wagenmakers AJM, Riddell MC. Carbohydrate Restriction in Type 1 Diabetes: A Realistic Therapy for Improved Glycaemic Control and Athletic Performance? Nutrients. 2019;11(5):1022. doi: 10.3390/nu11051022. PubMed PMID: 31067747.

Can Diabetes Affect Your Ability to Exercise in Hot Weather?

By Sheri Colberg, PhD

The arrival of summer brings to mind visions of people having fun in the sun and recreating on the beach, but hotter weather also creates greater risks related to dehydration and heat stress for people who are physically active outdoors. Aging by itself negatively affects the body’s ability to dissipate heat in both dry and humid environments (1), but having diabetes further increases the risk of developing heat stress during outdoor activities, especially when it’s hot and/or humid (2). Whole-body heat loss may be impaired due to abnormal skin circulation and decreased sweating (3), both of which can lead to increases in body temperature and heart rate.

People with type 1 diabetes (4) and type 2 diabetes (5) may have impaired regulation of body heat. In particular, athletes with type 1 diabetes may sweat less, especially when they are working out at more intense levels (4), and many adults with type 2 diabetes have a reduced ability to be active in the heat. The good news, though, is that these individuals with diabetes can still acclimate to doing aerobic or resistance training in hotter environments.

What do people need to do to acclimate? Adequate hydration is key to maintaining blood volume and blood flow, both of which affect body cooling during physical activities. Overheating in any environment occurs more easily when dehydrated (6). Dehydration leading to less sweating is more likely when glucose levels are elevated and can lead to chronic hyperglycemia (5). So, everyone needs to closely monitor and manage blood glucose during training or competition in the heat to avoid making any existing impairments in the ability to cool the body worse.

Plain water is usually effective for hydrating during activities lasting an hour or less. During longer workouts or events, water can also suffice for hydration, but sports drinks or other fluids may provide extra carbohydrate to keep blood glucose from dropping too much. In general, consuming about 1 liter of fluid per hour during activities in the heat is recommended (7)—but don’t take in too much or water intoxication can result. Hydrate after activities to restore fluids and electrolytes lost through sweat and breathing (8) and manage blood glucose.

Do the following to minimize the risk of exercise-related heat stress:

  • Avoid exercising during the hottest times of the day; choose morning or evening times
  • Stay out of direct sunlight during exercise whenever possible
  • Wear loose-fitting, light-colored exercise clothing
  • Take in extra fluid and electrolytes (e.g., salt) every day while acclimating
  • Don’t wait until you’re thirsty to drink fluids, and avoid alcohol since it’s dehydrating
  • Give yourself a couple of weeks to fully acclimatize to exercising in the heat
  • Try to stay cool until you start exercising, or exercise indoors
  • During hot-weather exercise, watch for signs and symptoms of heat-related illness
  • If unfit or new to exercise, be extra cautious when working out in the heat

References:

  1. Notley SR, Poirier MP, Hardcastle SG, et al. Aging Impairs Whole-Body Heat Loss in Women under Both Dry and Humid Heat Stress. Med Sci Sports Exerc. 2017;49(11):2324-32.
  2. Poirier MP, Notley SR, Boulay P, et al. Type 2 diabetes does not exacerbate body heat storage in older adults during brief, extreme passive heat exposure. Temperature. 2020;7(3):263-9.
  3. Notley SR, Poirier MP, Sigal RJ, et al. Exercise Heat Stress in Patients with and without Type 2 Diabetes. JAMA. 2019;322(14):1409-11.
  4. Carter MR, McGinn R, Barrera-Ramirez J, et al. Impairments in local heat loss in type 1 diabetes during exercise in the heat. Med Sci Sports Exerc. 2014;46(12):2224-33.
  5. Kenny GP, Stapleton JM, Yardley JE, et al. Older adults with type 2 diabetes store more heat during exercise. Med Sci Sports Exerc. 2013;45(10):1906-14.
  6. Colberg SR. Nutrition and Exercise Performance in Adults with Type 1 Diabetes. Can J Diabetes. 2020;44(8):750-8.
  7. Yardley JE, Colberg SR. Update on Management of Type 1 Diabetes and Type 2 Diabetes in Athletes. Curr Sports Med Rep. 2017;16(1):38-44.
  8. Evans GH, James LJ, Shirreffs SM, Maughan RJ. Optimizing the restoration and maintenance of fluid balance after exercise-induced dehydration. J Appl Physiol. 2017;122(4):945-51.

Key Exercises and Training for Aging Successfully and Living Your Best Life

As the years have rolled by, nothing has become more clear to me with each passing day than the fact that aging successfully requires a lot of work. When it comes to our bodies, nothing rings truer than “If you don’t use it, you lose it.” This is particularly true when it comes to preventing declines arising from disuse, but also when trying to slow down the normal impacts of aging.

The function of our bodily systems peaks at around age 25 and declines over time. As a result, your maximal aerobic capacity decreases over time, even with constant training, reflective of declines in maximal heart rate. What’s more, your balance ability gets worse (particularly after age 40), bones get thinner, muscles atrophy, reflexes get slower, and recovery from workouts takes longer. Aging is not for sissies (but it beats the alternative)!

The good news is that is it possible to at least slow how rapidly most of these systems decline by changing how you live your life. By including regular physical training, better nutrition, adequate sleep, and stress management, you can delay or prevent a lot of normal aging and reverse decrements caused by inactivity, neglect, disuse, and abuse of our bodies. (The only one we really can’t slow or reverse is our neurological decline.)

It starts to seem like preventing additional declines from inactivity or inadequate training gets to be a full-time job as you get older, and you have to keep adding in additional exercises, stretches, and activities. A fitness instructor recently confirmed that it’s a bit like playing whack-a-mole: fix one weak area or physical problem and another one pops up. Welcome to aging!

So what can you do to live your best life, physically and mentally? I would suggest adding at least these (and many other) critical exercises to your weekly routine:

Cardiorespiratory fitness: Cardio workouts with faster training intervals

In addition to doing regular cardio activities like walking, cycling, and swimming, add in some faster intervals into any workout, such as walking faster for 10 to 60 seconds at a time during your normal walk or doing a hill profile on a cardio training machine. Doing so will increase your fitness more and improve insulin sensitivity for longer. It’s also fine to do high-intensity interval training (HIIT) at least once a week, but start out slowly and progress slowly to prevent injuries and demotivation. Not all your workouts should be equally intense, and varying your aerobic activities also lowers the risk of getting injured.

Muscular strength and endurance: Resistance training exercises

It is easy to work on your muscle strength and muscle endurance by doing a series of resistance exercises targeting your major muscle groups (in the upper body, lower body, and core areas). Pick at least 8 to 10 exercises that cover all these areas and do them at least two to three days per week. It’s fine to use your own body weight, household items (like full water bottles), hand weights, or resistance bands as resistance—you don’t have to have access to a gym or leave home. Adding in these exercises to your weekly routine is critical to aging well and being able to live independently throughout your entire lifespan.

Balance ability: Standing on one leg at a time (and other balance exercises)

This simple exercise involves standing on one leg for a minute, switching to the other leg, and repeating. Have something you can grab onto nearby, such as the back of a chair. You can hold on with both hands, one hand, one finger, or nothing as you get better at balancing. To challenge yourself, move your free leg in different directions (e.g., out front, to the side, behind you) while standing on the other one, or practice standing on uneven surfaces, such as a cushion. If your balance ability is really getting to be an issue, include other balance training activities each week as well.

Joint mobility and cartilage health: Stretches for all your joints

Do a series of flexibility exercises that stretch your joints in all their normal directions to maintain and increase their range of motion. With aging, we are all losing flexibility and diabetes can accelerate this loss when extra glucose sticks to joint surfaces (cartilage) over time and makes them more brittle. Try to stretch at least two to three days per week. The older you get, the longer you should hold each stretch (up to a minute on each one), and you may need to add in specialized stretches (such as for your calves or hips) to really work tighter joints to enhance your mobility and balance ability.

Bone strength: Weight-bearing activities and/or resistance training exercises

Your bones stay stronger when you put normal stress on them regularly, such as carrying your own body weight around when walking or jogging or doing resistance exercises with your upper body or carrying grocery bags. If you stay sedentary, your bones will lose minerals faster and get thinned out more quickly, and non-weight-bearing activities like swimming and cycling just don’t have the ability to build bone as much as weight-bearing ones. Try to adequately stress your bones to stimulate the bone mineral density to stay higher—at least two to three days per week.

Basic mobility and self-care: Wall sits and/or sit-to-stand exercise

Until you start to get older, you seldom think about how difficult it can be to get up out of a chair or off the sofa. Many older people get heavier and weaker and start to have trouble doing these basic maneuvers, which are critical to living well independently. To improve your ability, practice doing wall sits, which involves sitting against a wall with your hips and knees at 90 degree angles and your feet straight below your knees for as long as you can. This exercise will also help prevent knee pain and problems. Alternatively, you can do sit-to-stand exercises where you sit on the edge of an armless chair and practice getting up without using your arms. (This is also often called the “getting up from the toilet” exercise.)

Sexual enjoyment (and incontinence): Kegel exercises

Also known as pelvic floor muscle training, Kegel exercises can help with stress incontinence (i.e., urinating a little when sneezing or laughing) and normal incontinence (both urinary or fecal), and they may enhance your sexual pleasure to boot. The easiest way to identify the pelvic floor muscles is to stop your urine flow while urinating or tighten the muscles that keep you from passing gas. To do Kegels, imagine you are sitting on a marble and pretend you’re lifting it up by tightening your pelvic muscles and holding them contracted for as long as you can; do this a few times in a row. When your muscles get stronger, you can do these exercises while sitting, standing, or walking. Both men and women can and should do Kegel exercises regularly.

A Potential New Oral Medication for Type 1 Diabetes and How It May Affect Exercise

Have you heard of TTP399? Despite its completely forgettable name used in clinical trials, this potential new oral medication may have the power to lower and stabilize blood glucose in people with type 1 diabetes (T1D). If approved, TTP399 (which would be given a spiffy new brand name) will be the first oral pill to treat T1D. You’ll still need insulin, but TTP399 should lower blood glucose without raising the risk of diabetic ketoacidosis (DKA), and it won’t increase the risk for low blood glucose either.

So, how does this new drug work and why should you get excited about it? TTP399 works on your liver to activate an enzyme called glucokinase. You may be wondering, what is glucokinase and why does it need to be activated? And why isn’t it already activated in people with T1D?

I actually know a thing or two about glucokinase given that my PhD work was in glucose and fatty acid turnover during exercise. As you may know, the liver plays a central role in maintaining a normal blood glucose level, which it accomplishes by storing or releasing glucose depending on your blood glucose levels and activities—assuming everything works well with insulin and glucagon release by the pancreas.

Normally, the beta cells of the pancreas make insulin while the alpha cells make glucagon. What happens in T1D is that insulin release from the pancreas is insufficient or absent altogether, and the usual balance of insulin and glucagon—with insulin rising after meals and glucagon rising during fasting and exercise—that signals the liver what to do to keep your blood glucose normal is lost. Even when you replace insulin through injections, pumping, or inhalation, it never reaches as high of levels as normal in the liver circulation, causing a “sleeping liver” with key metabolic enzymes never being activated. The result: Both a lesser storage of glycogen in the liver and an excess release of glucose after meals and overnight due to glucagon being unchecked by insulin.

This is why glucokinase activation is so important. Activated glucokinase stimulates glucose uptake from the blood and synthesis and storage of glucose in the liver as glycogen (1,2). Having it normally activated would make you need less insulin on a daily basis because your liver would take up and store blood glucose after meals like it is supposed to.

In the pancreas, activated glucokinase acts as a glucose sensor in the beta cells, allowing rising glucose levels to stimulate insulin secretion when glucokinase is activated in people with T2D or anyone with T1D with any insulin-making capacity left (3). In the alpha cells, glucagon secretion is normally triggered by hypoglycemia and suppressed by high glucose levels, but impaired suppression of glucagon is a hallmark of diabetes—in T1D due to insulin deficiency and in T2D due to insulin resistance and/or deficiency (4). Glucose sensing in the alpha cells can limit the release of glucagon but—you guessed it—that also requires activated glucokinase (4). When inactive, too much glucagon gets released and raises your blood glucose—even after meals when your levels are already higher.

How does this all impact exercise? If your liver has been stimulated by activated glucokinase to store more glycogen pre-exercise, you should have more to release to keep your blood glucose from dropping when you are active (since glucagon rises during physical activity), and you would be less likely to experience lows during and even following exercise. Sufficiently activated glucokinase in your pancreatic alpha cells should also reduce those pesky glucose elevations frequently experienced in the early morning hours by many people.

You really do want your glucokinase activation to be back up to normal in your liver and your pancreas, and TTP399 may just prove to be the way to do that in people with T1D. In the SimpliciT1 study (5), use of TTP399 resulted in both a decrease in A1C and in the amount of insulin that participants needed over 12 weeks, including 11 percent less insulin for meals, as well as two more hours a day with their glucose levels in an optimal range. Apparently, even with less insulin on board and a lower risk for hypoglycemia, people were not more likely to develop DKA, thus avoiding the major pitfall of medications like SGLT-2 inhibitors that have been used off-label (that is, without FDA approval) by some with T1D that can lead to DKA even with normal blood glucose levels.

TTP399 was recently given breakthrough therapy designation by the U.S. FDA. This designation provides the developer with added support and the potential to expedite development and review timelines for a promising new medicine. Let’s hope that the final trials being done on this medication prove it to be as effective as the earlier ones.

References:

  1. Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E. Glycogen metabolism in humans. BBA Clin. 2016 Feb 27;5:85-100.
  2. Matschinsky FM, Wilson DF. The Central Role of Glucokinase in Glucose Homeostasis: A Perspective 50 Years After Demonstrating the Presence of the Enzyme in Islets of Langerhans. Front Physiol. 2019 Mar 6;10:148.
  3. Toulis KA, Nirantharakumar K, Pourzitaki C, Barnett AH, Tahrani AA. Glucokinase Activators for Type 2 Diabetes: Challenges and Future Developments. Drugs. 2020 Apr;80(5):467-475.
  4. Basco, D., Zhang, Q., Salehi, A., Tarasov, A., Dolci, W., Herrera, P., et al. (2018). α-cell glucokinase suppresses glucose-regulated glucagon secretion. Nat. Commun. 9, 1–9.
  5. Klein KR, Freeman JLR, Dunn I, Dvergsten C, Kirkman MS, Buse JB, Valcarce C; SimpliciT1 research group. The SimpliciT1 Study: A Randomized, Double-Blind, Placebo-Controlled Phase 1b/2 Adaptive Study of TTP399, a Hepatoselective Glucokinase Activator, for Adjunctive Treatment of Type 1 Diabetes. Diabetes Care. 2021 Apr;44(4):960-968.

Sheri R. Colberg, PhD, is the author of The Athlete’s Guide to Diabetes: Expert Advice for 165 Sports and Activities (the newest edition of Diabetic Athlete’s Handbook). She is also the author of Diabetes & Keeping Fit for Dummies, co-published by Wiley and the ADA. A professor emerita of exercise science from Old Dominion University and an internationally recognized diabetes motion expert, she is the author of 12 books, 34 book chapters, and over 420 articles. She was honored with the 2016 American Diabetes Association Outstanding Educator in Diabetes Award. Contact her via her websites (SheriColberg.com and DiabetesMotion.com).

How to Address Those Nagging Joint Injuries and Pain

Back in late 2017, one of my columns addressed whether you can determine if your joint issues are related to being active, normal aging, or diabetes (SheriColberg.wordpress.com). The answer was that you really can’t determine the exact cause(s), but any or all of them may be contributors. Does it matter more if you know the underlying cause if you can figure out the best treatment? Let’s discuss this more in the context of my own recent injuries.

Over the past three years, I have continued to have nagging joint injuries or develop new ones, all while being as physically active as possible (and still aging and having type 1 diabetes). For example, I had an acute painful issue with the plantar fascia (arch) of my left foot after walking (with shoes on) on the beach for miles, which forced me to hobble around on the outer edge of that foot for weeks afterward and led to a stress fracture in my fifth metatarsal (outer foot bone) that took the usual 6-8 weeks to heal. I assumed it would be fine after healing, but when I resumed my normal 5-mile walks (on pavement, not the beach), I started experiencing pain around the outer side of my left ankle and foot—which I have been dealing with off and on now for close to three years. What do you need to know about dealing with similar chronic, nagging injuries? The following points are relevant:

#1: Determine the underlying issue

Even if you do not know the cause of your problem (such as aging or diabetes), it helps to know what the underlying issue is. In my case, my ankle/foot pain was due to inflamed peroneal tendons (peroneal tendinitis), which I first self-diagnosed and then had confirmed by a podiatrist. X-rays and other tests may be able to determine if you have arthritis in joints and allow you to rule out other issues. My current finger issues recently were identified by a hand doctor as a Dupuytren’s contracture and a trigger finger, both of which I could be more prone to due to genes, injury, or diabetes (1).

#2: Find the best treatment to fix the problem instead of just treating the symptoms

I tried many different remedies on my own to deal with my ankle/foot symptoms for years, including the traditional R.I.C.E. (rest, ice, compression, elevation), occasional ibuprofen, different shoes, supports in my shoes, and walking less far or less frequently, depending on the level of pain and inflammation. None of these treatments worked long-term. More recently, I revisited my podiatrist for a referral to a physical therapist—who finally helped me fix the real problem (and it was not the ankle inflammation). I had weak muscles in my lateral foot and a severe lack of flexibility in my calves and ankles; the tendinitis was a result of the way these problems made me walk.

#3: Most treatments involve both stretching and strengthening exercises

Although I thought I was doing plenty of regular stretching to stay flexible (since all of us are losing flexibility as we age, and diabetes can accelerate these losses), fixing my chronic ankle joint pain required going beyond the normal exercises I had in my repertoire. This is where the physical therapist helped tremendously. From her I learned that I had not been stretching effectively, neither long enough nor focusing on the right areas. In older age, people likely need to hold each stretch closer to 60 seconds total rather than just 15 to 30 seconds, and I had to do stretches other than my normal ones to overcome the tightness in my calf muscles. Not being able to dorsiflex my ankle normally due to inflexibility when walking was contributing to the problem. Even just typical loss of motion around joints with aging can interfere with people doing normal daily activities, and diabetes and physical inactivity can contribute to inflexibility. Especially in older individuals, some decreasing flexibility may be related to nerve dysfunction and not just to structural changes in the muscle-tendon unit (1-3), but stretching still helps regardless.

One other important aspect of overcoming my joint issue was learning the appropriate strengthening exercises to do. I have been consistent with resistance training for most of my adult years, but when it came to my left ankle and foot, my compensatory bad walking techniques had caused me to lose the strength needed to keep my foot from rolling out. I had to learn and frequently practice many exercises targeted at restoring the strength of my foot and ankle in order to walk properly (heel to toe) and reduce my ankle tendon irritation.

Adequately strengthening the muscles in various areas of our bodies is critical to managing and preventing many joint issues and pain. Working to strengthen a weak back and core muscles can reduce and prevent low back pain; exercises strengthening muscles around affected joints can lessen arthritic pain; and even Kegel (pelvic floor) exercises can help control urinary incontinence. In the case of an issue like Dupuytren’s contracture or trigger finger, too much stretching may actually aggravate the condition, but it still helps me to keep the surrounding muscles strong with targeted finger and hand exercises.

#4: Seek out expert help for solutions (if you need to)

It took a physical therapist to set me on the right path to overcome my ankle/foot problem, even though I consider myself to be quite knowledgeable about exercise, so don’t feel bad if you need to seek out expert help in learning the right exercises to do. Just keep in mind that disuse is the greatest contributor to muscle atrophy and weakness, although being too active (and bad form) can sometimes cause problems as well. In general, it takes regular (and specific) training exercises—for both flexibility and strength—to stay on top of joint and muscle health. In most cases, it is not just aging or diabetes alone that causes your joint issues.

References:

  1. Broekstra DC, Groen H, Molenkamp S, Werker PMN, van den Heuvel ER. A Systematic Review and Meta-Analysis on the Strength and Consistency of the Associations between Dupuytren Disease and Diabetes Mellitus, Liver Disease, and Epilepsy. Plast Reconstr Surg. 2018 Mar;141(3):367e-379e.
  2. Hirata K, Yamadera R, Akagi R. Associations between Range of Motion and Tissue Stiffness in Young and Older People. Med Sci Sports Exerc. 2020 Oct;52(10):2179-2188.
  3. Nordez A, Gross R, Andrade R, Le Sant G, Freitas S, Ellis R, McNair PJ, Hug F. Non-Muscular Structures Can Limit the Maximal Joint Range of Motion during Stretching. Sports Med. 2017 Oct;47(10):1925-1929.
  4. Konrad A, Tilp M. Increased range of motion after static stretching is not due to changes in muscle and tendon structures. Clin Biomech (Bristol, Avon). 2014 Jun;29(6):636-42.

Is Weight Loss or Physical Activity More Important for Preventing Type 2 Diabetes?

Ever since the U.S. Diabetes Prevention Program (DPP) multicenter trial was completed nearly two decades ago (1), we have known that it is possible to prevent, or at least delay, prediabetes (an insulin resistant state) from progressing into full-blown type 2 diabetes. Why? Diabetes risk was reduced by 58% in the “intensive lifestyle” (ILS) participant group and by 31% in the metformin (an oral glucose-lowering medication) participants compared to no intervention (“placebo” group). For participants who were 60 years or older, lifestyle changes worked much better to prevent diabetes than taking metformin (1,2).

As an exercise physiologist, what I have always disagreed with about the DPP trial is its greater emphasis on weight loss than on physical activity. Admittedly, ILS consisted of a goal of losing 7 percent of body weight (only 14 pounds if you weight 200) by following a low-calorie, low-fat, high fiber diet and doing at least 150 minutes per week of a moderate physical activity (like brisk walking). In a follow-up report (2), for every kilogram (2.2 pounds) of weight loss, type 2 diabetes risk was reduced by 16%.

However, in the DPP, both a lower percent of calories from fat and increased physical activity predicted weight loss. Typically, it is easier for people to lose some weight than to keep it off afterwards, and that study reported that increased physical activity was critical to maintaining a lower weight. Even among the 495 participants who failed to meet the weight loss goal of 7% loss the first year, those who exercised regularly still had a 44% lower diabetes incidence (without weight loss!), and only the regular exercisers kept the weight off (2). In my mind, that means that physical activity is likely more important.

For the 10-year DPP Outcomes Study (DPPOS) and the 15-year follow-up, all original DPP participants were offered intensive lifestyle management training (3,4). During the first 7 years, diabetes incidence rates decreased by 42% in those who had not been doing ILS or taking metformin previously (DPP placebo group) and by 25% in the DPP metformin participants (who had the option to keep taking metformin); by way of comparison, those in ILS during the DPP increased diabetes rates by 31% during follow-up (5). That seems like a horrible outcome for the DPP ILS participants who only had to keep up their lifestyle changes.

On further analysis, no combination of changes in weight, physical activity, diet, smoking, and antidepressant or statin use explained the DPPOS lower rates of diabetes progression in placebo and metformin groups, but…weight gain was associated with higher rates in the ILS group. That also seems like a bad outcome. Did these participants stop exercising or become less active during the follow-up study? Statistically speaking, physical activity was not a factor that accounted for their increased diabetes rates, but in practical terms, even small changes in activity can make a big difference in blood glucose and body weight management. It’s also important to note that the ILS group still had the overall lowest rates of diabetes incidence at the 15-year mark, even though they rose closer to the other groups (4).

Although the DPP established combined lifestyle improvements (diet, activity, and weight loss) as the best way to prevent type 2 diabetes, a more recent study attempted to determine how much exercise alone contributes, along with the optimal intensity of exercise since most DPP participants did brisk walking (6). Three study groups did varying amounts and intensities of exercise while the fourth followed diet and exercise strategies like the DPP to lose 7% of body weight. Interestingly, a higher amount of moderate-intensity exercise by itself (the equivalent of walking about 13.8 miles weekly) was very effective at improving how well people responded to consuming a large amount of glucose (via an oral glucose tolerance test) despite a relatively modest 2-kilogram (4.4-pound) loss of body fat, which suggests that a higher amount of moderate-intensity walking may work as well as combined approaches for preventing the progression to type 2 diabetes. It should be noted, however, that only the diet and exercise group experienced a decrease in fasting blood glucose levels in that study (6).

So, does physical activity matter? I still maintain that it is as important as—if not more important than—losing weight when it comes to preventing diabetes and managing insulin resistance (even if you have type 1 diabetes), especially since most people have trouble keeping the weight off and only regular physical activity is guaranteed to help you do that. Importantly, the latest follow-up study coming from the DPP just confirmed that I (and others) were right all along (7). In that study, cumulative diabetes incidence remained lower in the lifestyle compared with the placebo and metformin randomized groups and this difference could not be explained by changes in body weight. Examining the self-reported physical activity overall revealed that physical activity was inversely related to diabetes, meaning that the more active people were over time, the less likely they were to develop it, regardless of their body weight. Eureka!

Losing the right type of weight matters as well (that is, mostly fat and not much muscle), so if you are dieting, make sure you include regular activity (particularly resistance exercise) to retain more of your insulin-sensitive muscle mass (8).

References:

  1. Knowler WC, Barrett-Connor E, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346(6):393-403.
  2. Hamman RF, Wing RR, et al. Effect of weight loss with lifestyle intervention on risk of diabetes. Diabetes Care. 2006;29(9):2102-7.
  3. Diabetes Prevention Program Research Group, Knowler WC, et al. 10-year follow-up of diabetes incidence and weight loss in the Diabetes Prevention Program Outcomes Study. Lancet. 2009;374(9702):1677-86.
  4. Diabetes Prevention Program Research Group. Long-term effects of lifestyle intervention or metformin on diabetes development and microvascular complications over 15-year follow-up: the Diabetes Prevention Program Outcomes Study. Lancet Diabetes Endocrinol. 2015;3(11):866-75.
  5. Diabetes Prevention Program (DPP) Research Group, Hamman RF, et al. Factors affecting the decline in incidence of diabetes in the Diabetes Prevention Program Outcomes Study (DPPOS). Diabetes. 2015;64(3):989-98.
  6. Slentz CA, Bateman LA, et al. Effects of exercise training alone vs a combined exercise and nutritional lifestyle intervention on glucose homeostasis in prediabetic individuals: a randomised controlled trial. Diabetologia. 2016;59(10):2088-98.
  7. Kriska AM, Rockette-Wagner B, Edelstein SL, et al. The Impact of Physical Activity on the Prevention of Type 2 Diabetes: Evidence and Lessons Learned From the Diabetes Prevention Program, a Long-Standing Clinical Trial Incorporating Subjective and Objective Activity Measures. Diabetes Care. 2021;44(1):43-49.
  8. Colleluori G, Aguirre L, et al. Aerobic plus resistance exercise in obese older adults improves muscle protein synthesis and preserves myocellular quality despite weight loss. Cell Metab. 2019;30(2):261-273.e6.