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Pro Tips for Exercising with Diabetes

Figuring out when and how to exercise can be one of the most difficult parts of living with diabetes. At the ADA's 83rd Scientific Sessions, experts shared strategies for staying active with diabetes.

Having diabetes doesn’t mean you have to let go of the things you love doing, which may include playing sports. Exercise is an essential part of diabetes management, leading to improved weight management, reduction in cardiovascular disease risk factors, and great mental health benefits.

At the American Diabetes Association’s (ADA) 83rd Scientific Sessions, experts like Dr. Lori Laffel, chief of the pediatric, adolescent and young adult section at Joslin Diabetes Center, discussed the benefits and strategies for safely exercising with diabetes. Laffel pointed to the ADA’s Standards of Care, which recommend adults get 150-300 minutes per week of moderate-to-vigorous exercise and youth get 420 minutes per week of moderate-to-vigorous exercise.

But even with all of the evidence pointing to its benefits, managing exercise can be one of the most difficult parts of living with diabetes. There are multiple challenges to consider, such as abnormal insulin delivery and glucagon physiology, how stress hormones affect blood glucose, hydration, and more.

The good news is that you can still stay active with diabetes and engage in the sports you love. Famous athletes who have diabetes include five-time Olympic gold medalist Gary Wayne Hall Jr., recent Super Bowl champion Noah Gray, and the Women’s National Basketball Association’s 2022 third overall pick Lauren Cox.

Exercising just might mean a little more planning on your part. This includes paying special attention to the type of physical activity you’re doing, carb intake, and your insulin regimen, said Laffel.

How does exercise impact blood sugar?

It’s still difficult to know the degree to which exercise affects your blood glucose levels. According to Michael Riddell, professor of kinesiology and health sciences at York University, an optimal glycemic range is “unclear and very individualized for the athlete with diabetes.” Factors that influence one’s glucose response to exercise include the type of activity, time of day, whether you’ve recently taken insulin, what food was recently consumed, stress, sleep, and more.

Athletes who compete may want to consider how their levels vary between training days versus competitions. While it might not always be doable in practice, Riddell recommends a time in range of 70% during training and 75% on competition days – while paying special attention to minimizing hypoglycemia to less than 1%. For competitive athletes, other important things to manage include sleep, meals, basal/bolus insulin, hydration, and workout schedules.

The type, duration, and intensity of exercise are main factors that influence glucose response. Different forms of physical activity cause different glycemic trends that ultimately affect how you respond to diabetes management. For example, endurance activities (like walking, jogging, and cycling) tend to reduce glucose levels, whereas high-intensity interval training (HIIT) and resistance training tend to vary more so.

Laffel said that if you are engaging in intense exercise, know it can cause hyperglycemia and may increase your insulin needs during recovery time. The amount of carbs you should eat to maintain your desired glucose levels will depend on the intensity of your exercise.

Lower-intensity exercise typically means more carbs and less insulin needed and vice versa for higher-intensity exercise, explained Riddell. For context, about 50% of recreational athletes with type 1 diabetes prefer training and sometimes competing with a moderately low (100-200 grams per day), low (40-99 grams per day), or very low (<40 grams per day) carb diet.

Helpful guidelines and tech for exercise

Activity monitors and devices can significantly help with diabetes management while exercising. Connected pens and insulin pumps provide timely dosage; continuous glucose monitors (CGM) let you follow trends to guide your insulin dosing and carb intake; and automated insulin delivery (AID) can protect you from hypoglycemia and possible hyperglycemia.

Laffel provided a few basic guidelines if you’re engaging in aerobic exercise for more than 40 minutes. If you’re on multiple daily injections (MDI) or an open-loop pump, consider the following insulin adjustments:

  • For those on MDI, start with a 20% reduction in basal insulin dose.
  • For people on insulin pump therapy, reduce basal rate by about 50% (as a starting point) 1-2 hours before, during, and about one hour after exercise.
  • Reduce bolus insulin by 50% for meals or snacks two hours before and up to two hours after exercise.
  • At bedtime (or 7-11 hours following afternoon exercise) reduce your basal rate by 20% for up to six hours.
  • If you are engaging in unplanned aerobic exercise, eat a few extra carbs.
  • Use a CGM or monitor to check glucose before, during, and after physical activity.

According to Laffel, an overlooked but important part of exercising with diabetes is the cool-down period, which can be any sort of exercise that you consider easy, such as walking or a slow jog. Cooling down can reduce your risk of hyperglycemia after vigorous exercise. You should cool down for about 20 minutes. If your glucose levels remain high, you can consider conservative insulin correction (greater than 220 mg/dL).

Ultimately, there are many ways you can tailor diabetes management to work for your exercise plan. You should discuss your exercise regime with your doctor, as everyone’s needs are individualized and dependent on their lifestyle. 

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