I am 28. How should insulin be adjusted for exercise in T1D?

Question

Hello doctor,

I am a 28-year-old woman with type 1 diabetes since I was 12. I use an insulin pump and monitor my glucose with a CGM (continuous glucose monitoring). Still, lately I have been noticing sudden crashes during the night, even though my insulin settings have not changed. I also started exercising more recently and wonder if that is affecting things.

Can you explain how to adjust insulin for exercise, especially for women whose hormone cycles vary?
Should I alter basal or bolus?

Please help.

Thank you.

Answer 1

Hi,

Welcome to icliniq.com.

I have gone through your query and understand your concern.

As your physician, I want to reassure you that what you are experiencing is not uncommon. Sudden nighttime glucose drops can often be triggered by increased physical activity, especially when using an insulin pump and your body is still adjusting.

Exercise can increase insulin sensitivity for up to 24 to 48 hours afterwards, so even if your pump settings have not changed, your usual basal insulin may now be too much, particularly overnight.

In general, hormonal fluctuations during the menstrual cycle can further impact insulin sensitivity in women. Many women become more insulin-resistant in the luteal phase (after ovulation) and more sensitive around menstruation.

In your case, since the lows are occurring at night, the first step is to consider reducing your nighttime basal rate by 10 to 20 percent for the 6 to 12 hours following exercise. On workout days, you might also want a small, balanced snack before bed, with protein and complex carbohydrates.

It is typically better to adjust basal rather than bolus insulin for exercise unless you eat right before or after the workout. If your workouts are intense or longer, consider using a temporary basal rate reduction starting during exercise and continuing for a few hours afterwards.

Always track patterns using your CGM (continuous glucose monitoring), and work closely with your endocrinologist or diabetes educator to fine-tune your cycle and activity level settings.

I hope I have answered your question.

Let me know if I can assist you further.

Thank you.