Above you see part of the first page of a new consensus statement that comes from many of the individuals involved with the creation and launch of the new JDRF PEAK Performance Program, aimed at educating both clinicians and people with type 1 diabetes how to manage the complexities of being active. In my opinion, this recently published consensus statement on exercise and type 1 diabetes is long overdue and much needed. I managed to get the American Diabetes Association to let me chair an updated position statement (see my November blog) and include type 1 diabetes in it but, unfortunately, never just one addressing type 1 and exercise alone so this JDRF one fills a huge void.
The past decade has seen a growing number of publications related to diabetes management during exercise in people who have to either inject or pump insulin to stay alive. As you well know, whether insulin is injected or pumped, it is not being delivered where it normally ends up in a body that can release its own insulin, and this altered insulin delivery leads to alterations in hormones and blood glucose management by the liver. Normally, your liver would be able to either release or store glucose to keep your levels constant, but not without these proper hormonal signals.
Consequently, the only way you can keep your blood glucose levels normal (or near normal) with exercise is to take in carbohydrate/food, lower circulating insulin levels, or both during activities. Given that exercise is a huge stressor to normal metabolic control of blood glucose, it can make your diabetes more difficult to manage–even though exercising is generally beneficial for a number of other health reasons. This new consensus statement does an excellent job of covering all of the potential effects of engaging in differing physical activities, along with comprehensive management strategies involving changes in food intake and adjustments in basal and/or bolus insulin dosing. It also points out the many areas that need additional (or even any) research with regard to exercising with type 1 diabetes, either to enhance health or sports performance. Read it now if you haven’t already for some great advice!
(1) 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, Laffel LM. Exercise management in type 1 diabetes: a consensus statement, Lancet Diabetes Endocrinol. 2017 Jan 23. pii: S2213-8587(17)30014-1. doi: 10.1016/S2213-8587(17)30014-1. [Epub ahead of print]
I would like to let everyone know about a new position statement that covers all types of diabetes (type 1, type 2, and gestational) and prediabetes and addresses physical activity and exercise. It is based on an extensive review of more than 180 papers covering the latest diabetes research and includes the expertise of leaders in the field of diabetes and exercise from top research institutions in the US, Canada, and Australia.
The most notable recommendation calls for three or more minutes of light activity, such as walking, leg extensions or overhead arm stretches, every 30 minutes during prolonged sedentary activities for improved blood sugar management, particularly for people with type 2 diabetes. Sedentary behavior—awake time that involves prolonged sitting, such as sitting at a desk on the computer, sitting in a meeting or watching TV—has a negative effect on preventing or managing health problems, including diabetes. Studies have shown improved blood sugar management when prolonged sitting is interrupted every 30 minutes—with three minutes or more of standing or light-intensity activities, such as leg lifts or extensions, overhead arm stretches, desk chair swivels, torso twists, side lunges, and walking in place. Physical movement improves blood sugar management in people who have sedentary jobs and in people who are overweight, obese and who have difficulty maintaining blood sugars in a healthy range.
These updated guidelines are intended to ensure everyone continues to physically move around throughout the day – at least every 30 minutes – to improve blood glucose management. This movement should be in addition to regular exercise, as it is highly recommended for people with diabetes to be active.
Since incorporating more daily physical activity can mean different things to different people with diabetes, these guidelines offer excellent suggestions on what to do, why to do it and how to do it safely. It includes various categories of physical activity—aerobic exercise, resistance training, flexibility and balance training, and general lifestyle activity—and the benefits of each for people with diabetes.
Aerobic activity benefits patients with type 2 diabetes by improving blood sugar management, as well as encouraging weight loss and reducing cardiovascular risks. Movement that encourages flexibility and balance are helpful for people with type 2 diabetes, especially older adults. Regular aerobic and resistance training also offer health benefits for people with type 1 diabetes, including improvements in insulin sensitivity, cardiovascular fitness and muscle strength. Women who are at-risk or diagnosed with gestational diabetes are encouraged to incorporate aerobic and resistance exercise into their lives most days of the week. People with prediabetes are urged to combine physical activity and healthy lifestyle changes to delay or prevent a type 2 diabetes diagnosis.
Recommendations and precautions for physical activity and exercise will vary based on a patient’s type of diabetes, age, overall health and the presence of diabetes-related complications. Additionally, specific guidelines are outlined on monitoring blood sugar levels during activity. The statement also suggests positive behavior-change strategies that clinicians can utilize to promote physical activity programs.
(1) Colberg SR, Sigal RJ, Yardley JE, Riddell MC, Dunstan DW, Dempsey PC, Horton ES, Castorino K, Tate DF. Physical Activity/Exercise and Diabetes: A Position Statement of the American Diabetes Association, Diabetes Care, 39(11): 2065-2079, 2016. http://dx.doi.org/10.2337/dc16-1728
When researchers have done studies on adults with type 2 diabetes, although the participants as a whole have a positive average response to exercise training, as many as 15 to 20 percent of type 2 exercisers have been found to be “non-responders” (1). These are individuals who appear to be resistant to the beneficial effects of exercise training of all types because exercise training for them fails to improve their A1C (overall blood glucose control), body fat, body mass index, or other metabolic measures. But are there really exercise non-responders? And, if so, are you one of them?
Some researchers have blamed the exercise “non-response” observed in a minority of research subjects on inheriting bad genes. However, a large part of the data that these scientists used to “prove” their case came from animal research. For example, successive generations of rats have been bred until they had either a very high aerobic capacity or a low one, and the researchers then applied their findings that those animals with a low aerobic capacity don’t gain the same metabolic benefits directly to humans.
People are far from being similar to lab rats, though! We’re much more genetically diverse, and our muscles can improve their aerobic capacity with training, regardless of what genes we inherited from our parents (2). In fact, a recent review of 18 training studies concluded that normal training adaptations to aerobic exercise are possible in adults with type 2 diabetes (3), again suggesting the environment is a more viable explanation for those few who don’t respond like everyone else.
What are these environmental factors? For starters, a big issue with human aerobic training is that not all individuals in exercise studies end up training similarly, despite the good intentions of the researchers. I know from training hundreds of research subjects over the years that many older people don’t push themselves as hard as they could when they’re doing the initial exercise test (especially when riding a cycle that makes their legs hurt), and their training protocol is then set up based on a lower-than-actual maximal capacity. So, they may simply not be doing as much total training or expending as many calories during exercise as others in the study.
Many older adults with diabetes also have joint issues or health problems that limit their ability to exercise, including excess body fat, high blood pressure, or nerve damage in their feet. What’s more, what people eat is seldom controlled well in exercise studies, and taking in excess food can override the benefits of exercise, including limiting how long or high insulin action is elevated and blood glucose control after workouts (4). In other words, it’s entirely possible to negate the effects of the last bout of exercise and diminish its acute (and chronic) metabolic benefits by overfeeding.
Simply being less active during the rest of the day can also impact whether you experience the expected results of doing the training. Not surprisingly, people who are more active all day long and not just during training sessions fare better as far as their metabolic health is concerned, even when exercise training is the same for all participants in a study (5).
Even the medications you take can limit your responses to doing exercise training. The most commonly prescribed medication for type 2 diabetes is metformin, and taking metformin can blunt your normal metabolic response to exercise training (6). Taking statins to lower your blood cholesterol can cause some muscular problems that may limit your ability to exercise, as can some other medications commonly prescribed for other health problems.
Even if it’s not the environment that is holding you back and you do have some genetic traits that may limit your exercise response, that certainly doesn’t mean that you won’t gain a lot of other health benefits—both physical and mental—from being more physically active. There really is no evidence that the potential to response to exercise training is limited if you have type 2 diabetes, type 1 diabetes, prediabetes, or obesity; in fact, even breaking up prolonged sitting time has measurable metabolic benefits for everyone (7). So, get up and go be active doing whatever you enjoy the most—and be as active as you possibly can all day long. Your body will thank you for it!
- Stephens NA, Sparks LM: Resistance to the beneficial effects of exercise in type 2 diabetes: Are some individuals programmed to fail? J Clin Endocrinol Metab 2015;100(1):43-52
- Pruchnic R, Katsiaras A, He J, Kelley DE, Winters C, Goodpaster BH: Exercise training increases intramyocellular lipid and oxidative capacity in older adults. Am J Physiol Endocrinol Metab 2004;287:E857-862
- Wang Y, Simar D, Fiatarone Singh MA: Adaptations to exercise training within skeletal muscle in adults with type 2 diabetes or impaired glucose tolerance: a systematic review. Diabetes Metab Res Rev 2009;25:13-40
- Hagobian TA, Braun B: Interactions between energy surplus and short-term exercise on glucose and insulin responses in healthy people with induced, mild insulin insensitivity. Metabolism 2006;55:402-408
- Manthou E, Gill JM, Wright A, Malkova D: Behavioral compensatory adjustments to exercise training in overweight women. Med Sci Sports Exerc. 2010;42(6):1121-8
- Braun B, Eze P, Stephens BR, et al.: Impact of metformin on peak aerobic capacity. Appl Physiol Nutr Metab 2008;33:61-7
- Dunstan DW, Kingwell BA, Larsen R, et al.: Breaking Up Prolonged Sitting Reduces Postprandial Glucose and Insulin Responses. Diabetes Care 2012;35:976-983
Did you know that your body stores fat from excess calories in places other than fat cells? Both your muscles and your liver store extra fat as you gain excess fat weight (1). More fat storage in your muscles may decrease the removal of glucose from your blood, making muscles more resistant to insulin if you don’t exercise regularly (2; 3). Given that your muscles are responsible for the majority of blood glucose uptake in response to insulin, developing insulin-resistant muscles has a substantial impact on your blood glucose. Regular exercisers, paradoxically, can store more fat in their muscles without experiencing insulin resistance, suggesting that the total amount of fat stored there isn’t the critical component but rather how muscles respond to insulin (4).
The greater release of insulin that results from eating excessive amounts of carbohydrate may cause you to gain body fat because carbohydrates are usually converted into and stored as fat when you’re sedentary. If you store fat just in fat cells (particularly in the ones under the skin), you probably will not have as many health problems compared to putting it elsewhere. For example, storing extra fat in your liver may contribute to low-level inflammation, which can lead to the development of insulin resistance, diabetes, heart disease, and other metabolic disorders. Therefore, your liver (and whether or not it stores excess fat) may prove to be a crucial link between weight gain and the development of insulin resistance (1).
An insulin-resistant liver may lead to elevated blood fats and cholesterol levels that contribute to the development of heart disease. You can compound the problem by with dietary choices that contribute to your liver’s insulin resistance, including foods high in refined carbohydrates and highly processed ones. You can lower inflammation and improve your metabolic health with lifestyle changes, including exercising more (5). In fact, being active and eating more fiber naturally in your diet are likely the two most important changes you can make to lower your risk of all metabolic diseases (6).
You don’t have to lose a lot of weight: losing just ten pounds improves your insulin action, lowers inflammation, enhances good cholesterol and lowers the bad, improves metabolic efficiency, and reduces type 2 diabetes risk. Going on a diet to lose weight, however, is not the best long-term solution to managing your body weight or reducing your diabetes risk.
Why? Dieting does not work for most people. It becomes progressively harder to lose weight the longer you stay on a diet (thus making it harder for you to stay motivated to follow it); consequently, many people give up after a while.
A bigger problem is that you are not likely to keep off any weight that you do lose. More than nine out of ten dieters who have successfully lost weight ultimately regain the pounds they struggled to lose. If you go back to eating the same foods after your diet ends that you ate before, you will typically rebound by taking in excessive calories, particularly in the form of extra fat that quickly returns you to your former weight. In fact, most people gain back even more than they lost, regardless of the diet they followed. A greater percentage of the weight you regain is usually body fat, ultimately making your body fat higher than if you had never lost any weight.
While your body’s set point—or what you normally weigh—can change gradually over your lifetime, it remains the same over the relatively short time frame of a diet, unless you make permanent lifestyle changes. If you maintain high levels of daily physical activity while you’re losing weight, though, that will help you prevent gaining it back later on (7). So, if you have to choose between dieting and being more active to lose weight, always choose motion, even if weight loss is slower with exercise alone.
- Koska J, Stefan N, Permana PA, Weyer C, Sonoda M, Bogardus C, Smith SR, Joanisse DR, Funahashi T, Krakoff J, Bunt JC: Increased fat accumulation in liver may link insulin resistance with subcutaneous abdominal adipocyte enlargement, visceral adiposity, and hypoadiponectinemia in obese individuals. Am J Clin Nutr 2008;87:295-302
- Coen PM, Dube JJ, Amati F, Stefanovic-Racic M, Ferrell RE, Toledo FG, Goodpaster BH: Insulin resistance is associated with higher intramyocellular triglycerides in type I but not type II myocytes concomitant with higher ceramide content. Diabetes 2010;59:80-88
- Coen PM, Goodpaster BH: Role of intramyocelluar lipids in human health. Trends Endocrinol Metab 2012;
- Bergman BC, Butterfield GE, Wolfel EE, Casazza GA, Lopaschuk GD, Brooks GA: Evaluation of exercise and training on muscle lipid metabolism. Am J Physiol 1999;276:E106-117
- Zoppini G, Targher G, Zamboni C, Venturi C, Cacciatori V, Moghetti P, Muggeo M: Effects of moderate-intensity exercise training on plasma biomarkers of inflammation and endothelial dysfunction in older patients with type 2 diabetes. Nutr Metab Cardiovasc Dis 2006;16:543-549
- Herder C, Peltonen M, Koenig W, Sutfels K, Lindstrom J, Martin S, Ilanne-Parikka P, Eriksson JG, Aunola S, Keinanen-Kiukaanniemi S, Valle TT, Uusitupa M, Kolb H, Tuomilehto J: Anti-inflammatory effect of lifestyle changes in the Finnish Diabetes Prevention Study. Diabetologia 2009;52:433-442
- Wang X, Lyles MF, You T, Berry MJ, Rejeski WJ, Nicklas BJ: Weight regain is related to decreases in physical activity during weight loss. Med Sci Sports Exerc 2008;40:1781-1788
With all the exercise training fads out there, it can be hard to navigate the landscape with diabetes. I am frequently asked about the latest training techniques or gym trends, so I want to specifically address a recent craze, CrossFit training, with regard to whether it’s appropriate and/or advisable for people with diabetes.
In brief, CrossFit training is a strength and conditioning program consisting mainly of a mix of aerobic exercise, gymnastics (body weight exercises), and Olympic weight lifting. Its programming is decentralized, but its general methodology is used by thousands of private affiliated gyms around the world. CrossFit, Inc., licenses the CrossFit name to gyms for an annual fee and certifies trainers, but the actual programs vary tremendously from site to site.
A concerned young man with type 1 diabetes contacted me to ask whether it’s safe for him to do CrossFit. Although he was already doing and benefiting from CrossFit training, he became concerned about it after reading a blog online by a Paleo diet advocate named Robb Wolf who, in an article about CrossFit training and type 1 diabetes, blogged that since intense training causes the liver to release excess glucose during training, people with type 1 diabetes “may be better served by mild to low intensity activities. Power Lifting, due to the low volume, might be a good option.” (This blogger also claimed that “We have seen instance of people REVERSING type 1 diabetes with a Paleo diet because they put their autoimmunity in remission.” That statement alone should make you question his credibility. If you really want to read it, please just don’t believe everything you read online, especially his blog: http://robbwolf.com/2009/08/05/type-1-diabetes-and-crossfit/#sthash.CIZdVMvp.dpu.)
My perspective is that, if you’re young and healthy and just happen to have diabetes, you should be able to engage in CrossFit training without worrying excessively about your blood glucose levels going up temporarily from doing it. To control your blood glucose, you simply have to approach it like any other intense workout, which can cause your blood glucose to go up even in people without diabetes. If you use insulin, you’ll just need to check your glucose frequently and adjust your insulin doses to make sure you have enough to stay in control both during and following your CrossFit (or other) workouts. As a side note, doing some easy cardio exercise after an intense workout can help lower your blood glucose naturally. Also, keep in mind that you’re more likely to have a bigger rise in the early AM compared to doing the same exact training later in the day (due to having more glucose-raising hormones and less insulin on board in the morning, pre-breakfast).
CrossFit does carry some risks, however. The risk of injury from some of its exercises outweighs their benefits when they are performed with poor form in timed workouts (although there are similar risks from doing other high-intensity programs incorrectly). One concern in particular is that CrossFit’s extensive online community enables anyone to follow the program without proper guidance, increasing the risk of improper form or technique that leads to getting injured. I have heard of at least one young man who caused significant damage to the cartilage in both of his knees doing such training inappropriately. When undertaken correctly, CrossFit is not inherently bad or ineffective, but beginning exercisers starting such a program may be encouraged to do too much and not be able to discern between training to failure and simply getting a good workout.
By way of example, a young woman who was a physical therapist and a regular CrossFit participant woke the morning after a particularly grueling session consisting of hundreds of reps of arm exercises and found she could not bend her elbows. She was diagnosed in the emergency room with rhabdomyolysis (“rhabdo” for short), a condition in which damaged muscles break down rapidly. This is not the first time CrossFit has been associated with rhabdo as the workouts can be particularly grueling and excessive, although any strenuous exercise can cause it. It’s worrisome because rhabdo can lead to kidney failure when excess breakdown products of damaged muscle cells (myoglobin) are released into your blood (see a video by the Mayo Clinic about exercise-associated rhabdo: https://www.youtube.com/watch?v=Hy0uEPo8-7w). Severe symptoms like muscle pain, vomiting, and confusion are symptoms of greater muscle damage and possible kidney failure. If you ever have severe muscle pain and dark colored urine, get medical attention immediately.
Has your exercise performance been less than you’d hoped recently? There are many different things that can cause fatigue, but here are some potential causes (and solutions) to consider.
Inadequate rest time: A really simple answer to your exercise issues is that you may be getting through your workouts well, but then fail to perform when you have races and events simply because you didn’t take enough rest time to restore glycogen, repair muscle damage (caused by every workout), and fully recover. It’s critical to cut back on your workouts (“taper”) for at least 1-2 days before a big event. During that time, you also want to keep your blood glucose in good control so your glycogen levels will be as full as possible on race/event day.
Blood glucose and glycogen stores: Another thing to consider is your blood glucose control. It’s harder for your body to restore your muscle glycogen (stored carbs) between workouts unless you’re eating enough carbs and have functioning insulin available. Doing longer and harder workouts can deplete glycogen stores, and you may simply just not be restoring them fully fast enough due either to your carb intake or your blood glucose management. Your carb intake doesn’t have to be tremendous—probably just 40% of your total calories coming from carbs will suffice—but you may need more if you’re not eating enough calories. Your blood glucose absolutely needs to be in good control for your muscles to store all the carbs you need to exercise optimally, so make sure your insulin is adequate and working effectively.
Iron levels: For starters, having low iron stores can cause you to feel tired all the time, colder than normal, and just generally lackluster. You can get a simple blood test done to check your hemoglobin (iron in red blood cells) and your overall iron status (serum ferritins). It’s possible to be iron deficient without having full-blown anemia. If your body’s iron levels are low (due to diabetes or non-diabetes causes), taking iron supplements can help, along with eating more red meat since it has the most absorbable form of iron.
Magnesium deficiency: Most people also have issues with magnesium deficiency, especially if you take insulin or your blood glucose levels are not well controlled. Magnesium is involved in over 300 enzyme-controlled steps in metabolism, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation. If you’re deficient in this mineral, your exercise will be compromised and you may even experience some muscle cramping (unrelated to dehydration). It’s always good to eat more foods with magnesium in them—such as nuts and seeds, dark leafy greens, legumes, oats, fish, and even dark chocolate—but taking a supplement (magnesium in the aspartate, citrate, lactate, and chloride forms is absorbed better than magnesium oxide and sulfate) may help. Low magnesium can also lead to potassium imbalances, which can also affect your ability to exercise well.
B vitamin intake: For people with diabetes, thiamin deficiency is also a likely culprit for exercisers, especially if they’re not eating properly. In general, the eight B vitamins are integrally involved in metabolism and even red blood cells formation. Thiamin (B1) in particular can be depleted by alcohol intake, birth control pills, and more. People who take metformin to control diabetes can also end up deficient in vitamins B6 and B12, both of which are essential to nerve function and muscle contractions. Taking a generic B complex vitamin daily can help you avoid these issues, and excesses of most of the B vitamins are harmless (and end up in your urine).
Insulin delivery method: While insulin pumps can help manage blood glucose acutely, they deliver rapid-acting insulin analogs like Humalog, Novolog, and Apidra, and these altered insulins are metabolized in the body differently than the long-acting basal one called Lantus. Rapid ones have little to no insulin-like growth factor (IGF) affinity, and most adults are reliant on IGF to stimulate muscle growth and repair rather than human growth hormone (which is only higher in youth). Lantus does stimulate IGF one, though, so you may want to talk with your doctor about combining insulin pump use (for meal boluses) with Lantus (for basal insulin coverage) to get more IGF activity to promote muscle repair. (Go with Lantus, though, as Levemir is less effective at raising levels of bioactive IGF.)
Thyroid issues: Many people with diabetes also have thyroid hormone imbalances. Having lower levels of functioning T3 and T4 can cause early fatigue and poor exercise performance, among other things. However, it may not be enough to just check your main thyroid hormones (TSH, T3 and T4); you may also want to consider getting your thyroid antibodies checked if your thyroid hormones levels are normal and nothing else is helping your exercise (specifically check for antibodies to thyroid peroxidase), especially if you have celiac disease.
Still stumped? If you’ve been through this whole list and had everything check out okay, then consider other possible issues like your hydration status, daily carb intake (adding even just 50 grams per day to your diet may help), other possible vitamin and mineral deficiencies (vitamin D, potassium, etc.), statin use (some statins taken to lower blood cholesterol cause unexplained muscle fatigue), frequent hypoglycemia, and hypoglycemia-associated autonomic failure.