Author: Sheri R. Colberg, PhD, FACSM

Addressing how to balance blood glucose levels during (and after) exercise with type 1 diabetes is not new. In fact, it is likely the KEY topic to address to be successful at being physically active if you take exogenous insulin and want to prevent hypoglycemia or hyperglycemia during exercise. Strategies include changing insulin doses and/or supplementing with food, either of which can be done in myriad ways depending on the activity, timing and more.

A recent 2020 study revisited whether it works better to supplement with carbohydrates or lower bolus (mealtime) insulin doses before exercise to prevent lows (1). Its conclusionfor this particular group of subjects doing continuous, moderate-intensity cycle ergometer exercise for45 minuteswas that taking in 15 to 30 grams of carbohydrate when blood glucose levels decreased to 7.0 mmol/L (126 mg/dL) prevented hypoglycemia better. Okay, but.

My issue with these types of studies is not that theydontprove a pointthey dobut its that they prove a very, very narrow point. The results can only be generalized to people with the same physical fitness level, age, sex, and diet undertaking a specific type, intensity, duration, and timing of activity. Exercising with type 1 diabetes is so much broader than that. Moreover,itsnot just short-term insulin dosing or immediate carbohydrate intake that hasan impact on balancing blood glucose and affecting how successful you are at being active.

Whether participating in sports or physical activity on a recreational basis or striving to be a professional or Olympic athlete, anyone who takes insulin must pay attention to his or her unique nutritional and dietary patterns, including intake of macronutrients (carbohydrate, protein, and fat), micronutrients (vitamins and minerals), fluids, and supplements like caffeine to maintain metabolic and glycemic balance (2). Athletic performance aside, nutritional recommendations may also differ on an individual basis relative to exercise, glycemic management, and body weight goals. Balancing all these dietary factors can be challenging for individuals with type 1 diabetes, and many related aspects have yet to bethoroughly researched in this population.

Carbohydrates undeniably have the most immediate impact on blood glucose. Theymust be matched with adequate insulin doses to manage blood glucose peaks after eating (3), but protein and fat intake can impact insulin needs as well (4). When youre an active individual with type 1 diabetes, you must balance all your dietary choices before, during, and after exercise to manage blood glucose levels notjust toprevent lows or highs, but also for optimal performance and recovery from working out or competing. Its possible to eat many different ways,including low-carbohydrate (5), andthe best nutritional practices to optimize performance may or may not be best for blood glucose management, optimal health, and bodyweight simultaneously, potentially making achievingathletic and health goals difficult at times.

As for insulin dosing, people vary so muchabouttheir usual doses, insulin sensitivity, types of insulin used (basal and bolus choices), delivery (that is, insulin pump use vs. injections or inhalation), and more. It makes the whole balancing act that much more difficult, especially when blood glucose responses vary with the type of activity being done, including how long, how hard, how often, and under which environmental conditions. Even hydration status matters! Given how limited studies by nature must be to limit all these conditions, it takes individual trial-and-error to figure out what works best to maintain blood glucose levels in areasonably tight (and hopefully normal) range for everysingle activity bout.

Many insulin users have still managed to figure out how to compete athletically at the highest levels. However,it is far from simple when balancing blood glucose levels with these many confounding variables (6).Itscertainly still worth it to be physically active with type 1 diabetes, just a challenge!

References:

Sheri R.Colberg, Ph.D., is the author ofThe Athletes Guide to Diabetes: Expert Advice for 165 Sports and Activities(the newest edition oftheDiabetic Athletes Handbook). She is also the author ofDiabetes & Keeping Fit for Dummies,co-published by Wiley and the ADA. A professor emerita of exercise science from Old Dominion University and an internationally recognized diabetes motion expert, she is the author of 12 books, 30 book chapters,and over 420 articles. She was honored with the 2016 American Diabetes AssociationOutstanding Educator in Diabetes Award.Contact her via her websites (SheriColberg.com and DiabetesMotion.com).

See more about how to balance blood glucose levels and exercise safely in our therapy center.

Read more:
Exercising with Type 1 Diabetes: The Insulin-Food Balance Challenge - Diabetes In Control