Updated Federal Physical Activity Guidelines: Do They Apply to People with Diabetes?

shutterstock overweight exercise pixIn mid-November 2018, the U.S. Department of Health and Human Services finally released new physical activity guidelines (as a 2nd edition) to update their previous set from a decade before (1,2). Various activity guidelines for adults with diabetes have been updated several times in the interim, including a 2010 position statement on exercising with type 2 diabetes (3) published jointly by the American College of Sports Medicine and the American Diabetes Association; a 2016 ADA position statement on exercise and physical activity for all types of diabetes (4); and a consensus statement on being active with type 1 diabetes published in The Lancet in 2017 (5).

In those three sets of recommendations specific to diabetes, it was clear that everyone with diabetes can benefit from being more regularly active. Adults with diabetes should undertake a variety of activities, including aerobic, resistance, flexibility, and balance training (the last one particularly for adults over 40 or anyone with neuropathy), as well as stay more active on a daily basis just doing lifestyle activities or sitting less for better blood glucose management and weight control. The activity recommendations for adults and youth with diabetes have essentially been the same for everyone else of a similar age without diabetes.

So, what do the new federal guidelines add to the mix, if anything? Based on a review of the current research, the biggest change from the previous set of guidelines is likely that you don’t need to be active for a minimum of 10 minutes at a time for it to be beneficial to fitness and well-being. Given that many studies in the past decade have shown that breaking up sedentary behavior with short (3-minute) breaks can alter metabolism for the better, these recommendations are not surprising. They also recommend that people should sit less overall, again not a shocking guideline at this point. Studies done with people with diabetes have reached the same conclusions, so these updates certainly apply to everyone.

Another change in the federal guidelines applies to the weekend warriors: they now state that adults can derive similar health benefits if they perform all their weekly recommended physical activity in a single day or two rather than over the course of multiple days. However, whether this guideline applies as directly to people with diabetes is questionable. Past guidelines (3,4,5) have recommended that adults with diabetes not go more than two days without doing some physical activity, and many have recommended doing daily or near daily exercise for better blood glucose management. Given that the enhancing effects of your last bout of physical activity on insulin sensitivity may only last 2 to 72 hours, it seems unlikely that people with diabetes will gain all the same benefits by being a weekend warrior only—at least not when it comes to blood glucose management through reduced insulin resistance. For now, the recommendations for people with diabetes to do some type of exercise at least every other day will likely remain in place for that reason.

Finally, the new guidelines expanded out recommendations for all adults to get 150 minutes of moderate aerobic activity or 75 minutes of intense activity (or a combination thereof) each week to include up to double that amount—300 minutes moderate or 150 minutes intense aerobic training—and beyond for additional benefits. As if the bar weren’t set high enough already, you now have to find even more time to be active to gain optimal health benefits. While we already knew this was true, apparently the federal government also now recognizes how important it is for all of us to be the anti-couch potato and get as much as activity as possible to optimize our collective health! Luckily, the guidelines for doing resistance training at least two days a week are still unchanged, although we all know that doing three nonconsecutive resistance workouts a week is a preferable goal to maximize muscle gains and prevent losses of muscle (where we store carbohydrates) from aging and disuse.

In summary, these new federal physical activity guidelines really did not change what we should be doing already: getting at least 75 to 150 minutes of aerobic exercise weekly depending on its intensity (but closer to double that amount for optimal health), doing resistance training at least twice a week (but preferably three), stretching regularly, working on our balance ability if we’re older, moving more, sitting less, getting up more often, and taking the stairs instead of the elevator. So, go get active!

References:

  1. Physical Activity Guidelines for Americans, 2nd Edition, 2018. Accessed at https://health.gov/paguidelines/second-edition/.
  2. Executive Summary: Physical Activity Guidelines for Americans, 2nd Edition, 2018. Accessed at https://health.gov/paguidelines/second-edition/pdf/PAG_ExecutiveSummary.pdf.
  3. Colberg SR, Sigal RJ, Fernhall B, Regensteiner JG, Blissmer B, Rubin RR, Chasan-Taber L, Albright AL, and Braun B. Exercise and type 2 diabetes: The American College of Sports Medicine and the American Diabetes Association: Joint position statement. Diabetes Care, 33(12): e147–e167, 2010.
  4. Colberg SR, Sigal RJ, Yardley JE, Riddell MC, Dunstan DW, Dempsey PC, Horton ES, Castorino K, and Tate DF. Physical activity/exercise and diabetes: A position statement of the American Diabetes Association. Diabetes Care, 39(11); 2065–2079, 2016.
  5. Riddell MC, Gallen IW, Smart CE, Taplin CE, Adolfsson P, Lumb AN, Kowalski A, Rabasa-Lhoret R, McCrimmon RJ, Hume C, Annan F, Fournier PA, Graham C, Bode B, Galassetti P, Jones TW, Millán IS, Heise T, Peters AL, Petz A, and Laffel LM. Exercise management in type 1 diabetes: a consensus statement. Lancet Diabetes Endocrinology, 5:377–390, 2017.
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How Diets Impact Performance (in Active People with Diabetes)

French friesMany insulin users have chosen to go “low-carb” to better manage diabetes, which may or may not impact how well they perform in athletic events. How do many athletes with diabetes who swear by extreme low-carb diets that are either high in fat (like a keto diet) or higher protein (e.g., Dr. Bernstein) perform? How do their dietary choices impact both their blood glucose management and their ability to be active?

Although I personally choose to follow a more balanced diet with a moderate intake of lower-GI carbohydrates (making up less than 40 percent of my total calories), it’s mostly because I prefer plant-based foods. As a semi-vegetarian (choosing to not eat mammals), I don’t particularly like poultry, fish, and seafood that much either but eat some because it makes managing my blood glucose easier. I avoid most bread and white flour products and strictly limit how much rice, white potatoes, highly processed carb foods, and other rapidly-absorbed, high-GI carbohydrates I eat. Natural, plant-based fiber is a staple in my diet. I also exercise daily doing a variety of activities and experience very few lows when active. I don’t actively eat low carb, but I am carb-conscious and careful with my intake.

Here’s what some other active individuals with diabetes say about their diets and performance (excerpted from The Athlete’s Guide to Diabetes, Feb. 2019):

”I eat mostly low carb, but find that I often need to eat more carbs after sports in order to prevent overnight lows. I try to eat 30 percent of my daily calories from carbs, 30 percent protein and 40 percent fat each day.” — Molly M. (Canada)

“I stick to a low-carb diet. I eat a lot of meats, salads, eggs, and nuts. I avoid bread, pasta, processed food, and any type of sugar unless my blood glucose is low. I found that a low-carb diet makes it way easier to control my blood glucose throughout the day, especially during exercise. The more Humalog I use, generally the more tired I feel, and I also gain weight much easier and faster.” — Aaron G. (Minnesota)

“I normally eat a plant-based (vegetarian) nutritional lifestyle. I almost always work out fasted in the morning as I’ve discovered this is how I feel best and how I can maintain the best control over my blood glucose. I also practice intermittent fasting, with my first meal each day generally at about 11:00 a.m. and my last food intake around 8:00 p.m. My carb intake varies daily, and I don’t particularly aim to eat low carb as I eat a lot of fruit, sweet and regular potatoes, and beans. I eat eggs almost every day and rarely eat any kind of dairy product.” — Daniele H. (Pennsylvania)

“I eat reasonably low carb most of the time, though I do “carb up” for race days and tests sometimes (for performance reasons).” — Jennie B. (United Kingdom)

“I have been following a low-carb, high-fat diet for a couple of years. It makes it easier to keep blood glucose levels stable and keeps me full so less tempted to snack between meals. Though I don’t eat low enough carb to stay in ketosis. I eat 40 to 60 grams of carbohydrate per day.” — Andrea L. (France)

“I follow the metabolic efficiency diet. I eat about 125 to 150 grams of carbs per day with a diet focused on low glycemic carbs, fiber, healthy fats, and proteins. I avoid white flour and high glycemic foods.” — Conor S. (Pennsylvania)

“I stick to low carb unless in an environment of heavy training (marathon training). Consuming periodic glucose during endurance exercise and events can optimize my performance. I eat no fast food and a healthful diet full of greens and fish.” — Bill K. (Pennsylvania)

“Per Dr. Bernstein’s protocols, I eat low carb, moderate protein. I typically exercise in the morning and do not have active bolus insulin on board. I will eat small portions of dried fruit to bring my blood glucose up to 120 if it’s below that when I start. If I am going to do a race that will last more than 90 minutes, I will use UCAN 60 minutes before the race for slow acting carbohydrate during the event.” — Jason S. (New York) 

“I eat low-carbohydrate, high-protein, high-healthful fat meals. I recently cycled from Perth to Sydney, solo and unsupported in a time frame of 20 days, following low carb. As a fat-adapted athlete, this also disproved any theories that such exercise must be performed consuming a high-carbohydrate diet.” — Neil M. (Australia)

“I am, for the most part, on a Paleo diet. My carb intake is ~20 to 40 grams a day. By not needing to cover a large card intake, my boluses are less, thus I am not partaking in an odyssey of hours of either being hugely high or low due to a miscalculation. The law of small numbers is the key here.” — Jay H. (Wisconsin)

“Changing my diet to no starchy carbs has been magic. I dropped Lantus from more than 30 units down to 18 per day since dropping ALL starchy carbs. I eat no breads, pasta, cereal…The carbs I consume include veggies only. Most of my workouts now require no insulin management, and I seldom get low.” — Tom S. (Texas)

“I am carb-conscious. I do not eat low carb but make smart carb decisions. I aim to eat unprocessed, homemade food as much as possible. I love cooking in the backcountry and enjoy finding recipes that are dehydrated, lightweight, nutritious, and carb-rich for trekking days, and fueling.” — Jen H. (Canada)

“I was most helped by switching my diet and way of handling my diabetes to the Dr. Richard K. Bernstein method. I spent 47 and a half years stuffing glucose in my face all day long when I was skiing, hiking, or swimming just to keep my blood sugar above 100 (5.6) and then having it fly up to the 200 to 300s later. Now that I’m eating very low carb, this problem is greatly minimized. Eating this way has significantly flattened my blood glucose graph and prevented the precipitous, scary lows of the past. I’m so thankful to have found this way of handling type 1 diabetes.” — Mary Alice (California)

“I tend to eat low on the glycemic index and very little gluten. I substitute bean noodles for wheat, and quinoa is a staple. I eat a lot of slow-cooked meals with beans and vegetables. Breakfast is usually full-fat Greek yogurt. During trail races, I eat hard-boiled eggs and potatoes, items that provide nutrition, but don’t require a bolus. I don’t drink sports drinks or anything with sugars that need insulin. For low correction, I eat dried fruit which I find is kinder on the stomach than simple sugars in sports drinks. I don’t eat Gu or other sports gels. The less insulin in my system around exercise the better. This is not to be mistaken for low-carb or low-calorie diet; it’s just low-GI.” — Blair R. (California)

Can Exercise Overcome Impact of Air Pollution on Diabetes Risk?

China air pollutionIt’s known that lack of exercise, poor eating habits, genetics, and lifestyle factors can all contribute to the onset of prediabetes and type 2 diabetes. I have spent many years touting the benefits of lifestyle change to prevent and manage these health conditions—and in some cases reverse them. Exercise is a particularly important lifestyle management tool because of its ability to lower inflammation (the underlying cause of insulin resistance) naturally.

But what being active by itself is not enough to overcome the negative environmental effects? Studies have been coming out for over a decade already examining the association between the onset of type 2 diabetes and persistent organic pollutants (POPs) like those found in pesticides, as well as air pollution emitted by cars and trucks. While we usually think of air pollution as mainly contributing to respiratory problems and lung diseases, there’s mounting evidence that it is also implicated in health conditions like type 2 diabetes.

A recent systematic review and meta-analysis (1) on studies conducted in Europe and North America reported a positive association between air pollution and risk of developing type 2 diabetes. In a recent study (2), air pollution was found to have contributed to 3.2 million new diabetes cases in 2016, or about 14 percent of the total, globally. In the United States, air pollution has been linked to 150,000 new cases of type 2 diabetes each year. Although less evidence has been collected in developing countries where air pollution concentrations are much higher in many of them, long-term exposure to air pollution (including both ambient particulate matter and gaseous pollutants) has been reported to be associated with an increased risk of type 2 diabetes and higher fasting blood glucose levels, especially in individuals who were younger or overweight or obese, in 33 different regions of China (3).

Fresh off another trip to China (and exposure to an excess of smoggy air) where I lectured about the importance of lifestyle management to prevent and manage diabetes, I still find it hard to assess exactly how much of the environmental impact of poor air quality that exercise can overcome. Even though exercise is anti-inflammatory in nature, particulate matter and other toxins in the air are breathed in and lead to inflammation in the body, a state underlies most metabolic diseases, including insulin resistance, obesity, type 2 diabetes, heart disease, and more. Insulin resistance is present long before the onset of type 2 diabetes and results not only from inherited and lifestyle factors but also likely from environmental conditions. Unfortunately, developing countries that are more dependent on the use of coal are at greater risk. One in two people in China already has prediabetes or type 2 diabetes (compared to one in three in the U.S.). Rates of cigarette smoking are higher in China as well, and few, if any, regulations are in place to reduce exposure to second-hand smoke in the cities and even in office settings in many Chinese cities. (The cigarette smoke was heavy in one fitness/recreational area full of treadmills that I recently walked through in a building in Nanjing, China.)

So, then, how much of the inflammatory effect of polluted air can the anti-inflammatory properties of exercise can cancel out? Although we can’t control all the air that we breathe and even if healthy lifestyle habits including a better diet, more physical activity, improved gut health, and a weight loss regimen are not enough to overcome the effects of environmental pollution, it’s still likely that lifestyle improvement can drive down the risk of getting type 2 diabetes or improve your ability to manage it. Just do your best to limit your exposure to particulate matter in the air by exercising indoors on days with worse air quality (regardless of where you live), wearing a mask to limit your exposure to air pollution when outdoors, and avoiding cigarette smoke (both indoors and outdoors) as much as possible.

                                                                                                                                                           

References cited:

  1. Eze IC1, Hemkens LG, Bucher HC, Hoffmann B, Schindler C, Künzli N, Schikowski T, Probst-Hensch NM. Association between ambient air pollution and diabetes mellitus in Europe and North America: systematic review and meta-analysis. Environ Health Perspect. 2015 May;123(5):381-9. doi: 10.1289/ehp.1307823.
  2. Bowe B, Xie Y, Li T, Yan Y, Xian H, Al-Aly Z. The 2016 global and national burden of diabetes mellitus attributable to PM2·5 air pollution. Lancet Planet Health. 2018 Jul;2(7):e301-e312. doi: 10.1016/S2542-5196(18)30140-2.
  3. Yang BY, Qian ZM, Li S, Chen G, et al. Ambient air pollution in relation to diabetes and glucose-homoeostasis markers in China: a cross-sectional study with findings from the 33 Communities Chinese Health Study. Lancet Planet Health. 2018 Feb;2(2):e64-e73. doi: 10.1016/S2542-5196(18)30001-9.

Engage in Cross-Training to Get More Fit

SB pool side view.jpgIf you’re like a lot of other people, you may get bored doing the same physical activities day after day. More than half people who start exercise training programs drop out in the first six months. So, what you do to keep your workouts fresh sometimes matters more for getting the most out of training and staying with it. For these reasons (and more), you may want to consider doing cross-training.

Cross-training covers a lot of ground, including combining different types of activities (like cardio and resistance training) in one workout, doing both during the week, or including other types of training in your routine. For example, you may want to do a variety of activities on a weekly basis. For example, you can walk on Monday, Wednesday, and Friday but swim on Tuesday and take dance classes on Saturday.

Cross-training is recommended because it:

  • Uses several different activities to help you reach your exercise goals
  • Adds variety to your workouts
  • Helps fight insulin resistance
  • Leads to lower doses of diabetes medications for many people
  • Gives you flexibility in your program (for example, substituting indoor machines for outdoor walking if it’s raining outside)
  • Reduces injuries because you don’t repeat the same movement all the time
  • Minimizes boredom because you’re always changing up your exercises
  • Uses different muscles so more of them get the benefit of exercise training
  • Makes your daily activities easier on your joints and body
  • Keeps your body challenged to adapt and improve in different ways
  • Allows you to rest some muscles so they can recover from workouts without stopping you from exercising altogether on other days
  • Helps you develop new exercise skills and proficiencies

What cross-training ensures above all else is the ability to continue being active for the rest of your life and more motivated to move your body. Nothing is worse than getting sidelined from your regular training due to overuse or acute injuries caused by being active. Constantly stressing your body in the same way can lead to tendinitis in joints, bursitis, tendon ruptures, muscle tears and pulls, and possibly acute injuries. Each activity you do stresses your muscles and joints differently, so doing a variety lowers your chances of getting an injury.

In addition, cross-training helps you deal with any activity-related injuries without losing all your conditioning while waiting for the injury to heal. If you have lower leg pain, you can still work out your upper body doing other activities and vice versa. Try to alternate weight-bearing activities like walking with non-weight-bearing ones (for example, swimming and stationary cycling) to avoid injuring another part of your body while waiting for an existing injury to heal.

You also add variety to your exercise program when you include activities like walking, cycling, rowing, swimming, arm cycling, weight training, yoga, and more. You have more flexibility to choose different options based on your time constraints, the weather, and other factors. Mixing up your activities allows you to work a variety of muscles. Each activity recruits either different muscles altogether or the same ones in different patterns, allowing you experience a wider use of the muscles in your whole body.

Many people do find that when they engage in a variety of activities — some of them more enjoyable to them than others — they’re more willing to put up with the ones they don’t like just to be able to do the others on alternate days. So, in addition to making your workout routines more enjoyable, cross-training can help you fend off the boredom that’s more likely to pop up when you don’t like doing activities you feel forced to do.

Avoid Weight Gain From Treating Lows and From Insulin Use

Weight gain

It’s possible to gain weight from treating too many bouts of hypoglycemia. I addressed this topic over a decade ago, but it remains relevant and worth revisiting, along with addressing some new insights on weight gain in general with insulin use.

Weight Gain from Treating Lows

Although you can’t avoid treating a low, everything you use contains calories (at least until mini and nasal doses of glucagon are available) and those extra (albeit medically necessary) calories can still end up as excess body fat. Some heavily training athletes have reported gaining fat rather than getting leaner from all their workouts due to chasing a lot of exercise lows. Avoid gaining extra body fat by treating each low precisely to limit calories. Don’t just grab the nearest candy bar when it may take just one glucose tablet to bring your blood glucose back to normal if you have a minimal amount of insulin on board.

The best advice is to start with 4 to 15 grams of a rapid-acting sugar (preferably glucose), and only take in more glucose or follow it with a balanced food or drink if your low doesn’t resolve itself within 10 to 15 minutes or if you anticipate needing protein or fat in your system to prevent later lows, such as after a long workout or if you took too much insulin. Overtreating your lows just leads to rebound hyperglycemia, more insulin to bring it back down, and potentially another low later — followed by more calories and potential weight gain.

Weight Gain from Insulin Use

In addition to lowering blood glucose, the hormone insulin promotes fat storage, and if you often end up taking too much, it can make you gain extra fat weight. You can adopt some strategies to keep weight gain from happening from insulin or other diabetes medications, regardless of what type of diabetes you have.

Why is using insulin often associated with weight gain? When you use it, your blood glucose is (usually) in a tighter range, and you stop losing some calories as glucose in your urine like you do when your blood glucose is running on the high side. Also, as mentioned, you can gain weight from having to eat extra to treat any lows caused by insulin or other medications. (Remember, even if you have no other choice than to treat hypoglycemia, calories are still calories.) You may find that cutting back on refined carbohydrates that require more insulin to cover them, exercising regularly, and checking your blood glucose to avoid taking too much of any weight-inducing medications will help you avoid gaining fat weight.

Most people diagnosed with type 1 diabetes gain some weight as soon as they start using insulin. Many of them lost weight before diagnosis — some of it muscle — so not all the weight regain is necessarily bad (some is from muscle mass). However, you can gain excess weight from taking too much daily insulin and treating lows or even from taking the right amount of insulin but eating too many calories.

It’s advisable to not give up exercise, but you should still avoid gaining extra fat if you can because it is often associated with being more insulin resistant and may require you to take even larger doses of insulin. You can lower your insulin needs by staying regularly active. Readjusting your ratio of basal to bolus insulin — specifically, lowering your basal doses and raising your pre-meal insulin — without increasing your total daily insulin dose may also prevent weight gain with type 1 diabetes.

Also, try to keep your insulin needs as low as possible because the more you take, the greater your potential for causing lows that lead to weight gain is. During any physical activity, your muscles can take up blood glucose and use it as a fuel without insulin. Following exercise, your insulin action is heightened for a few hours up to 72 hours. During that time, you need smaller doses of insulin to have the same effect. With that in mind, adjust your insulin doses downward to prevent lows after exercise that cause you to take in extra calories to treat them.

Finally, you may be able to avoid weight gain by looking at the type of insulins you’re using. For example, once-daily Levemir used by people with type 2 diabetes causes less weight gain and less frequent hypoglycemia than NPH insulin, even combined with use of rapid-acting injections of meal insulin. The same is likely true when using Lantus, Basaglar, Toujeo, and Tresiba. In type 1 diabetes, individuals end up eating less when using Levemir compared to Lantus, leading them to gain less weight. It also helps to dose with fast-acting insulins for the amount of food you actually eat rather than eating to match your pre-meal insulin doses.

Using Diabetes Technologies like CGM During Exercise

Daniele HargenraderA topic that comes up frequently nowadays is the use of diabetes technologies with exercise. When I surveyed close to 300 active individuals with diabetes, more than 60 percent used an insulin pump (which is well above the national average), but even more of these exercisers—over 75 percent—wear a continuous glucose monitoring (CGM) device (1). The technology fervor has grown even louder since the FDA recently granted approval in the United States to an implantable, three-month CGM sensor called Eversense (made by Senseonics). Can you benefit from using these CGM and other devices, especially when active?

Given the challenges associated with exercise, using almost any of the latest technologies can be beneficial for managing your diabetes and health. For example, blood glucose meters give you immediate feedback on your starting levels and single point-in-time exercise responses, whereas CGM devices offer the opportunity for making better decisions in real-time based on glucose values and trends. Insulin pumps offer a more fine-tuned ability to regulate basal insulin levels and bolus doses. Moreover, closed-loop systems (even hybrid ones) integrating pump and CGM use have the potential to allow you to avoid glucose lows and highs during and following workouts. All forms of technology have inherent drawbacks, but it’s possible to overcome most of their issues with planning and knowledge.

Let’s focus on the use of CGM devices. Their accuracy has been improving over time, but they’re all still limited by the fact that there’s a lag of at least six to 20 minutes between the glucose they measure in interstitial spaces (between your skin cells) and actual blood glucose. This lag can be even greater during times when your blood glucose is changing rapidly during exercise (2). CGM users may also have problems getting the device to stay in place, similar to issues experienced by pump users with adherence of their infusion sets to the skin (1). Other reported challenges include sensor accuracy (2,3), variability in performance between sensors, breakage of sensor filaments, transportation of the sensor display, and inability to calibrate CGM during exercise (4). (If given the option, use an integrated watch to display values during exercise.) Anecdotally, exercisers have reported a “compression effect” when wearing the CGM sensor under compression shorts (1). This results in a greater lag time, presumably due to a lesser blood flow to skin in compressed areas. Although technical failures during exercise are possible with the newer versions of these monitors, CGM is still likely to be the wave of the future when it comes to monitoring and managing blood glucose.

However, the cost of using CGM devices is another issue that may limit their widespread adoption. For instance, Dexcom, Medtronic, and Senseonics technologies all cost about $7 to $8 per day to use, but the Eversense implantable one additionally requires a physician office visit to get the sensors implanted and removed every three months (although if approved, the 180-day XL model will reduce these costs by halving the required physician visits). All three of these systems are more expensive than the FreeStyle Libre, which costs about $4 to $5 per day but doesn’t have a wearable transmitter (although some people have come up with a workaround for this using the Ambrosia BluCon device with app for mobile phones); the Libre also lacks real-time alerts.

Insurance reimbursement has gotten more reasonable since CGM devices were first introduced over a decade ago, but it’s still spotty and prejudicial. Currently, only one (Dexcom) model is covered by Medicare for anyone with type 1 diabetes age 65 and over. Although people with type 2 diabetes—especially those using insulin—can also benefit from using CGM, coverage for them has been an even harder sell to insurance companies so far. In any case, the number of model choices has declined recently, and their cost is still quite prohibitive for most people without insurance coverage and even for some with larger insurance copays.

If you don’t have access, can’t afford, or don’t want the hassle of wearing a CGM device, it is still viable for you to use a blood glucose meter to exercise safely and effectively. Remember, just having access to that simple monitoring tool can make all the difference in the world when it comes to managing exercise. Make the most of any tools at your disposal!

                                                                                                                                                           

 References:

  1. Colberg, S. Diabetic Athlete’s Handbook, 2nd Champaign, IL: Human Kinetics, 2019 (in press)
  2. Taleb N, Emami A, Suppere C, Messier V, Legault L, Chiasson JL, Rabasa-Lhoret R, Haidar A: Comparison of two continuous glucose monitoring systems, Dexcom G4 Platinum and Medtronic Paradigm Veo Enlite system, at rest and during exercise. Diabetes Technol Ther. 18(9):561-7, 2016
  3. Herrington SJ, Gee DL, Dow SD, Monosky KA, Davis E, Pritchett KL: Comparison of glucose monitoring methods during steady-state exercise in women. Nutrients, 4:1282-1292, 2012
  4. Bally L, Zueger T, Pasi N, Carlos C, Paganini D, Stettler C: Accuracy of continuous glucose monitoring during differing exercise conditions. Diabetes Res Clin Pract, 112:1-5, 2016.

Going Low-Carb as an Athlete with Diabetes

There has been a lot of interest recently in going “low-carb” to better manage diabetes, particularly type 1. At present, a large clinical study (1) is being undertaken in Scandinavia to examine the effects of very low-carb eating on blood glucose levels in adults with type 1 diabetes. For years, a very low-carb diet championed by Dr. Bernstein has been the main one followed by some with diabetes, until the last decade when fad weight loss plans like the LCHF (low-carb, high-fat, or Keto) and Paleo Diets have been become mainstream not just for losing weight, but also for their purported ability to boost to athletic performance and improve blood glucose management.

All these eating plans are very low in carbohydrates, but differ in the types of non-carb macronutrients or foods they recommend. Dr. Bernstein’s plan advocates higher protein intake and only 30 grams of carbs daily. The LCHF Diet gets 70% of calories from fat, 15% from carbs. Paleo Diet eating focuses on “natural” foods that nomadic early man supposedly ate (higher protein). Honestly, LCHF diets remind me of the no-carb, starvation regimen that everyone with type 1 diabetes had to go on to survive for a few months or years after diagnosis back before insulin was discovered in 1921. Have we really come full circle back to that diet in mainstream eating for diabetes? This question is particularly relevant to athletic individuals with diabetes. We have often preached the importance of carb loading (think “pasta party”) for endurance athletes prior to events. Can they perform at the top of their game while eating very few carbs?

At least one study in type 1 diabetes has shown that it’s possible to balance blood glucose levels and prevent lows while doing long-duration endurance events and consuming 75 grams of carbs per hour, like many nondiabetic endurance athletes do (2). For intermittent sports like soccer and rugby, it also appears that ingesting 30 to 60 grams of carbs per hour has the greatest impact on performance when fatigue or hypoglycemia are more common, such as towards the end of a game (3) (although this has only been studied in nondiabetic athletes).

That said, it also appears possible to adapt to using more fat as a fuel after becoming keto-adapted from low-carb eating. Highly-trained, keto-adapted ultraendurance athletes have extraordinarily high rates of fat oxidation, but their use of muscle glycogen and its repletion during and after a 3-hour run are similar to athletes on high-carb diets (4). Some questions remain as to whether this improves performance in most events; likely, it does not, but performance is likely at least maintained (5). For instance, keto-adapted, off-road cyclists experience greater fat use, but higher heart rates at the same workload during training following LCHF diets containing only 15% of daily calories from carbs (6). With their average calorie intake, though, this amounts to nearly 150 grams of carbs daily, much more than many low-carb advocates allow in their diets.

To my knowledge, no studies to date have been conducted on keto-adaptation and performance in exercisers with diabetes. However, I recently surveyed over 275 active individuals with diabetes to collect information to update my 2009 book (7), Diabetic Athlete’s Handbook, as a second edition is coming out in Spring 2019. I was surprised by the large number of athletes claiming to be following very low-carb dietary regimens. Based on their responses, it appears entirely possible to undergo fat adaptation and exercise regularly—at least when engaging in endurance type training and events. These exercisers worry less about getting hypoglycemic during events as they have lower levels of insulin on board, but many others accomplished the same reduction in the risk of lows simply by not taking bolus insulin within a few hours of being active (even if eating more daily carbs).

There are several caveats to these survey results. All normal dietary patterns by these active individuals (most with type 1 diabetes) were self-reported, and I did not analyze their actual daily carbohydrate intake. Some claimed to eat only 20 grams of carbs a day, but it’s possible they weren’t including carbs from every food, including the many avocados (12 grams of carbs per medium one), olives (2-3 grams per 10 olives), and nuts they were consuming. Any carbs taken in during activities, even if taken to prevent or treat lows, count towards daily total intake. What’s more, if an average active individual consumes about 2,000 calories per day, getting 15% of calories from carbs (like most LCHF diets advocate) still equates to 75 grams per day, which is not nearly as low as the 20-30 daily grams many of these athletes claimed to be eating.

So, how low-carb do athletes with diabetes really need to go? In all likelihood, it depends on the sport and level of athlete. Sure, most of us can benefit from avoiding or limiting our intake of refined carbs and foods with a higher glycemic index to better manage our diabetes, but going to the extreme of avoiding nearly all carbs may not be necessary. If you do decide to try a lower-carb diet, keep in mind that adapting to training with fewer daily carbs requires several weeks, so don’t just cut carbs for a few days and expect to feel good during any type of exercise.

                                                                                                                                                                   

References:

  1. Lennerz, B.S., A. Barton, R.K. Bernstein, R.D. Dikeman, C. Diulus, S. Hallberg, E.T. Rhodes, C.B. Ebbeling, E.C. Westman, W.S. Yancy Jr, and D.S. Ludwig. Management of type 1 diabetes with a very low-carbohydrate diet. Pediatrics May 7, 2018. doi: 10.1542/peds.2017-3349. [Epub ahead of print]
  2. Adolfsson, P., S. Mattsson, and J. Jendle. Evaluation of glucose control when a new strategy of increased carbohydrate supply is implemented during prolonged physical exercise in type 1 diabetes. European Journal of Applied Physiology 115:2599–2607, 2015
  3. Baker, L.B., I. Rollo, K.W. Stein, and A.E. Jeukendrup. Acute effects of carbohydrate supplementation on intermittent sports performance. Nutrients 7:5733–5763, 2015
  4. Volek, J.S., D.J. Freidenreich, C. Saenz, L.J. Kunces, B.C. Creighton, J.M. Bartley, P.M. Davitt, C.X. Munoz, J.M. Anderson, C.M. Maresh, E.C. Lee, M.D. Schuenke, G. Aerni, W.J. Kraemer, and S.D. Phinney. Metabolic characteristics of keto-adapted ul-tra-endurance runners. Metabolism 65:100–110, 2016
  5. Burke, L.M. Re-examining high-fat diets for sports performance: did we call the “nail in the coffin” too soon? Sports Medicine Auckland New Zealand 45: 33–49, 2015
  6. Zajac, A., S. Poprzecki, A. Maszczyk, M. Czuba, M. Michalczyk, and G. Zydek. 2014. The effects of a ketogenic diet on exercise metabolism and physical performance in off-road cyclists. Nutrients 6:2493–2508, 2014
  7. Colberg, Sheri. Diabetic Athlete’s Handbook. Champaign, IL: Human Kinetics, 2009