What precautions should a type 1 diabetic take when exercising?

Question

Hello doctor,

I am a 29-year-old man with type 1 diabetes, diagnosed when I was 12. I have been reading about new research on exercise and blood sugar control.

I currently use an insulin pump and continuous glucose monitor, but I still struggle with glucose fluctuations during and after workouts.

I love running and weightlifting, but I often experience hypoglycemia during long runs or delayed hyperglycemia after intense lifting sessions.

I have tried adjusting my basal rates, but it is still a hit or miss. Are there any new guidelines or research findings on managing blood sugar for type 1 diabetics who exercise regularly?

I am particularly interested in learning about optimal timing for workouts, pre-exercise fueling, and post-exercise insulin adjustments.

Please help.

Thank you.

Answer 1

Hello,

Welcome to icliniq.com.

I read your query and can understand your concern.

During aerobic activities like running, your body burns glucose quickly, which can lead to hypoglycemia if not managed properly.

On the other hand, intense anaerobic exercises like weightlifting can trigger the release of stress hormones like adrenaline and cortisol, which can lead to a rise in blood sugar afterward, causing delayed hyperglycemia (elevated blood sugar levels).

Monitoring the timing of your workout relative to your last meal and insulin dose is key. For many people with type 1 diabetes, working out after a meal when insulin is at its peak can increase the risk of hypoglycemia (fall in blood sugar level). It might help to plan workouts when insulin levels are lower.

For example, cardiovascular exercises such as running in the late morning or early afternoon may minimize the risk of hypoglycemia. Evening strength training sessions can help reduce delayed hyperglycemia, but this varies by individual, so experimenting is essential.

Before longer runs, eating a small amount of fast-acting carbohydrates without taking additional insulin can help prevent hypoglycemia.

It is recommended to reduce basal insulin by around 20 to 50 percent before long aerobic sessions like running, and even more if your exercise lasts longer than an hour. After anaerobic activities like weightlifting, you may need to increase your basal insulin ( a slow-acting type of insulin) temporarily or give a small bolus (medicine) to counteract the hyperglycemia that sometimes follows.

Continuous glucose monitoring (CGM) can be a great help here, giving you real-time data to adjust your insulin more.

After exercise, it is common to experience a delayed drop in blood sugar, sometimes hours after the workout, especially at night.

This is more likely after prolonged aerobic exercise. Research suggests eating a snack with both carbohydrates and protein post-exercise, such as a small protein shake or yogurt with fruit, can stabilize your blood sugar.

You may also consider adjusting your overnight basal insulin rate after heavy exercise to prevent nighttime hypoglycemia.

There is some research on closed-loop systems (also known as artificial pancreas systems); I suggest you discuss it with your endocrinologist regarding this. Also, a physical examination by a doctor in a hospital is a must.

I hope this helps.

Thank you, and take care.

Regards.