Insulin Dependence and Exercise

If you or someone you know has diabetes, exercise can be scary. Common thoughts like, "Have I eaten enough beforehand?" or "Am I exercising too hard for my own good?" may go through your mind. Always follow guidance from your doctor, but hopefully these tips can help you if you have type 1 or type 2 diabetes! 

It is well-known that regular physical activity is important for anyone with or without type 1 or type 2 diabetes. However, managing blood glucose levels can be difficult when exercising for insulin-dependent diabetics and those trying to maintain or lose weight when food intake needs to be increased to accommodate a certain intensity or duration of exercise (Zaharieva & Riddell, 2017). The general recommendations are to get at least 150 minutes of moderate to vigorous activity or at least 75 minutes of vigorous activity each week, exercising on at least 3 days each week, and not allowing more than 2 consecutive days without exercise in order to maintain insulin sensitivity levels (Colberg, 2017). How long and how intense an exercise session is needs to be taken into consideration as different types of exercise have different recommendations for managing blood glucose levels (Ehrman et al, 2013, p. 105).  

According to Reibe et al., (2018) recommendations include:

• Monitoring blood glucose levels before, during, and after to ensure safety of performing exercise as well as avoiding onset of hypoglycemia later.
• Exercising at a consistent time each day to maintain consistent glucose levels.
• Exercising with a partner or under supervision to reduce the risk of a hypoglycemic event.
• Consuming up to 15g of carbohydrate prior to exercising when glucose levels are less than 100mg/dL.
• Appropriately progressing in both resistance and aerobic training to prevent injury or adverse effects of beginning a new exercise regimen. 

Additional recommendations by Ehrman et al., (2013) include:

• Exercising when it is most convenient to monitor and control blood glucose levels. 
• Avoiding exercise when insulin levels are high, glucose control is poor, or when ketones are present.   
• Avoiding exercise late in the evening to reduce risk of hypoglycemia while asleep.
• Maintaining proper hydration. 

Exercising safely and maintaining safe levels of blood glucose while doing so is a matter of considering the starting blood glucose levels (which is why it is important to monitor this beforehand) as well as the type of activity that will be performed. As mentioned, different durations and intensities of exercise require specific considerations.   

Ehrman et al., (2013) has a variety of recommendations for exercising with blood glucose levels less than 100mg/dL:

• Low intensities and short durations (bike ride or walk less than 30 minutes) a pre-workout snack containing 5-10g carbohydrate should be consumed.
• Moderate intensities and moderate durations (jogging for 30-60 minutes) a pre-workout snack containing 25-45g carbohydrate should be consumed. 
• Moderate intensities and long durations (biking for 60 minutes) a pre-workout snack containing 45g carbohydrate should be consumed. 

Additionally, exercising with blood glucose levels greater than 100mg/dL but lower than 180mg/dL Ehrman et al., (2013) has different recommendations:

• Low intensity and short duration = no pre-workout snack.
• Moderate intensity and moderate duration = 15-30g carbohydrate.
• Moderate intensity and long duration = 30-45g carbohydrate.
• One caveat to these recommendations is that medication may need to be adjusted if one is trying to lose weight to avoid an increase in food.  

Finally, the Mayo Clinic (2020) advises stopping the activity if blood glucose levels drop below 70mg/dL or beginning to feel shaky, weak, or confused. If this happens, it is recommended to consume 15g of a fast-acting carbohydrate and to re-check blood glucose levels until they return to at least 70mg/dL. Once returning to a safe range, it is OK to continue the exercise if desired. Afterwards, it is also important to have a snack of a slow-acting carbohydrate to prevent post-exercise hypoglycemia.  

Hopefully these tips can help you exercise with confidence especially if you are an insulin-dependent diabetic!

References:

Colberg S. R. (2017). Key Points from the Updated Guidelines on Exercise and Diabetes. Frontiers in endocrinology, 8, 33. https://doi.org/10.3389/fendo.2017.00033 

Ehrman, Gordon, Visich, & Keteyian. (2013). Clinical Exercise Physiology. Human Kinetics. 

Riebe, D., Ehrman, J.K, Liguori, G., & Meir, M. (Eds.). (2018). ACSM’s guidelines for exercise testing and prescription. (10th ed.). Wolters Kluwer.

Mayo Clinic. (2020). Diabetes and exercise: When to monitor your blood sugar. Retrieved from: https://www.mayoclinic.org/diseases-conditions/diabetes/in-depth/diabetes-and-exercise/art-20045697#:~:text=Eat%20a%20small%20snack%20containing,pre%2Dexercise%20blood%20sugar%20range 

Zaharieva, D. P., & Riddell, M. C. (2017). Insulin Management Strategies for Exercise in Diabetes. Canadian journal of diabetes, 41(5), 507–516. https://doi.org/10.1016/j.jcjd.2017.07.004