Category Archives: Diabetic Athletes

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.
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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

Do Diabetic Athlete Survey by May 15

DiabeticAthleteHandbookWebcover

Are you physically active and do you have diabetes (of any type)? Now is your chance to share how you manage your diabetes regimen while doing a variety of activities!

A new edition of Dr. Sheri Colberg’s book, Diabetic Athlete’s Handbook, is coming out in Spring 2019. Please complete the diabetic athlete survey at the link below no later than May 15 for possible inclusion.

https://www.diabetesmotion.com/athlete-survey

Please pass the survey on to everyone else you know who is active with diabetes. Thanks for your time and input!

New book on fitness and diabetes

My latest book, Diabetes & Keeping Fit for Dummies, was released this week, just in time to help you start the new year out right. It covers everything you need to know about getting or staying fit with diabetes or prediabetes. Even if you don’t have diabetes and want to improve your insulin action and prevent type 2 diabetes, this book is for you! Check it out today! Available on Amazon.com or Dummies.com.

Exercise to Lower Your Risk of Dying (Prematurely) with Type 1 Diabetes

Bob Stewart Jumping (crop)Much of the research on length of life for individuals living with type 1 diabetes is pessimist, which makes a new study released recently a breath of fresh air. Data were collected for the ongoing nationwide, multicenter, Finnish Diabetic Nephropathy (FinnDiane) Study that tracked the death rate of 2,639 study participants for an average of 11.4 ± 3.5 years (1).

In this study, participants’ leisure time physical activity was reported via a self-report questionnaire. Importantly, their physical activity and its intensity, duration, and frequency were examined related to dying from all causes and from cardiovascular events; some of these adults with type 1 diabetes already had diabetic kidney disease.

The researchers also looked at potentially confounding factors like sex, how long people had been diagnosed with type 1 diabetes and how old they were when they got it, as well as physical measures like their systolic blood pressure, triglycerides (blood fats), BMI (body mass index), and HbA1c (a measure of overall blood glucose control over two to three months).

The conclusions of this study came as no surprise to me: exercise is associated with a lower risk of premature death from cardiovascular or any other cause in adults with type 1 diabetes. Overall, 270 people died during the follow-up period, 127 of whom had kidney disease. Only exercise intensity was associated with cardiovascular mortality, with intense activity being best for preventing early death from cardiovascular events. Both how much total physical activity they got and how frequently they exercised were associated with a lower risk of dying from any cause. Prior studies have shown that exercise frequency may also matter in preventing such events, with a higher frequency of physical activity lowering the risk (2).

People with type 2 diabetes have already been shown to have a lower risk of premature death when they are physically active (3); this is also true for the adult population in general (4; 5). However, not as many studies have looked specifically at the association between physical activity and lower mortality risk in adults with type 1 diabetes. Type 1 diabetes has previously been associated with a shorter lifespan in many adults with it, particularly related to endothelial dysfunction and cardiovascular disease (6).

Earlier studies, such as the DCCT, have shown that keeping blood glucose levels in a more normal range can help lower the risk of diabetes-related complications in people with type 1 diabetes. Most deaths in this population are related to either cardiovascular events or kidney failure. Exercise has an innate ability to lower oxidative stress, which has been implicated in the development of many complications, as well as improve endothelial function (6). While regular physical activity is associated with a lower risk of early death in adults with and without type 2 diabetes, this study is one of the first to examine this association in type 1 diabetes.

While the exact amount of exercise needed to lower the risk of cardiovascular events is unknown and not determined by this study, doing any activity is arguably better than remaining sedentary. As in people without diabetes, intense activity likely is even more cardioprotective than moderate or light activity.

However, the exercise in this study was self-reported and only collected at the start of the study, making it is hard to draw definitive conclusions about how much exercise people need to do and how intense it needs to be to reduce the risk of dying.

In conclusion, as confirmed by this latest study, being physically active on a regular basis is critical to living long and well with type 1 diabetes. Remaining sedentary is far worse for your health and your longevity, so go get active!

                                                                                                                                                           

References cited:

  1. Tikkanen-Dolenc H, Waden J, Forsblom C, Harjutsalo V, Thorn LM, Saraheimo M, Elonen N, Tikkanen HO, Groop PH: Physical Activity Reduces Risk of Premature Mortality in Patients With Type 1 Diabetes With and Without Kidney Disease. Diabetes Care 2017;16:dc17-0615
  2. Tikkanen-Dolenc H, Waden J, Forsblom C, Harjutsalo V, Thorn LM, Saraheimo M, Elonen N, Rosengard-Barlund M, Gordin D, Tikkanen HO, Groop PH: Frequent and intensive physical activity reduces risk of cardiovascular events in type 1 diabetes. Diabetologia 2017;60:574-580. doi: 510.1007/s00125-00016-04189-00128. Epub 02016 Dec 00124.
  3. Loprinzi PD, Sng E: The effects of objectively measured sedentary behavior on all-cause mortality in a national sample of adults with diabetes. Prev Med 2016;86:55-57
  4. Biswas A, Oh PI, Faulkner GE, Bajaj RR, Silver MA, Mitchell MS, Alter DA: Sedentary time and its association with risk for disease incidence, mortality, and hospitalization in adults: a systematic review and meta-analysis. Ann Intern Med 2015;162:123-132
  5. Chau JY, Grunseit AC, Chey T, Stamatakis E, Brown WJ, Matthews CE, Bauman AE, van der Ploeg HP: Daily sitting time and all-cause mortality: a meta-analysis. PLoS One 2013;8:e80000
  6. Bertoluci MC, Ce GV, da Silva AM, Wainstein MV, Boff W, Punales M: Endothelial dysfunction as a predictor of cardiovascular disease in type 1 diabetes. World J Diabetes 2015;6:679-692

Exercise Management in Type 1 Diabetes: A Consensus Statement

JDRF Consensus Statement Cover

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!

Reference:

(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]

 

 

Use Exercise to Prevent Activity-Induced Lows

Willa D soccerYou may potentially be able to prevent, treat, or reverse impending hypoglycemia (low blood glucose) during exercise by some novel means (1). One mechanism is short sprints, while another is to alter the order in which you do different types of exercise.

Sprints: Doing a 10-second sprint either before or immediately after moderate exercise keeps blood glucose levels stable for at least two hours afterwards (2). Actually, this technique works anytime during exercise, but it doesn’t reduce the amount of carbohydrate needed to prevent hypoglycemia during the eight hours following such a sprint (3).

Sprinting will have a limited effect if you have high levels of insulin in your system or a blunted hormonal response. However, having been low beforehand doesn’t appear to diminish your body’s ability to respond to a short sprint by releasing enough glucose-raising hormones like adrenaline to raise blood glucose (4).

It’s also possible to keep your blood glucose higher during exercise by interspersing four-second sprints into an easier workout every two minutes or so (sort of like doing interval training) (5). These effects are due to a greater glucose release by your liver during exercise and less glucose uptake by muscles during exercise and recovery (6).

So, whenever you start to feel low during exercise, trying sprinting as hard as you can for 10 to 30 seconds to induce a greater release of glucose-raising hormones. This works best when you have only a limited amount of insulin circulating in your bloodstream and may not prevent hypoglycemia if you have a lot of injected or pumped insulin on board. When the hormonal effects wear off, though, be careful as you can develop hypoglycemia since sprinting uses up more of your muscle glycogen (stored carbs) that have to be replaced with blood glucose (3).

Exercise Order: Another strategy you can use for preventing exercise-induced lows is related to the order of the types of exercise you do (cardio and resistance training) (1). Blood glucose levels tend to fall more during moderate cardio training and less afterwards compared to resistance training, which causes less of a decline during and more overnight (7).

Doing both activities in one day can be done strategically. If you’re starting out with your blood glucose on the low side, do resistance training first, followed by cardio to keep your glucose higher throughout the first half of your workouts. If you’re starting out higher, begin with cardio training first (assuming it’s moderate and not intense) to lower your blood glucose levels and follow it up with resistance work, which keeps blood glucose stable (8).

Try these techniques today to stay on top of your lows and remain more active. Your body will thank you for it!

References:

  1. Yardley JE, Sigal RJ. Exercise strategies for hypoglycemia prevention in individuals with type 1 diabetes. Diabetes spectrum : a publication of the American Diabetes Association 2015;28:32-8.
  2. 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;50:1815-8.
  3. Davey RJ, Bussau VA, Paramalingam N, et al. A 10-s sprint performed after moderate-intensity exercise neither increases nor decreases the glucose requirement to prevent late-onset hypoglycemia in individuals with type 1 diabetes. Diabetes care 2013;36:4163-5.
  4. Davey RJ, Paramalingam N, Retterath AJ, et al. Antecedent hypoglycaemia does not diminish the glycaemia-increasing effect and glucoregulatory responses of a 10 s sprint in people with type 1 diabetes. Diabetologia 2014;57:1111-8.
  5. Dube MC, Lavoie C, Weisnagel SJ. Glucose or Intermittent High-Intensity Exercise in Glargine/Glulisine Users with T1DM. Med Sci Sports Exerc 2013;45:3-7.
  6. Fahey AJ, Paramalingam N, Davey RJ, Davis EA, Jones TW, Fournier PA. The effect of a short sprint on postexercise whole-body glucose production and utilization rates in individuals with type 1 diabetes mellitus. The Journal of clinical endocrinology and metabolism 2012;97:4193-200.
  7. Yardley JE, Kenny GP, Perkins BA, et al. Resistance versus aerobic exercise: acute effects on glycemia in type 1 diabetes. Diabetes care 2013;36:537-42.
  8. Yardley JE, Kenny GP, Perkins BA, et al. Effects of performing resistance exercise before versus after aerobic exercise on glycemia in type 1 diabetes. Diabetes care 2012;35:669-75.