Insulin pump basal adjustment for exercise in type 1 diabetes: a randomised crossover study

Area of Science:

• Endocrinology
• Metabolism
• Exercise Physiology

Background:

• Type 1 diabetes management requires careful insulin adjustment, especially around physical activity.
• Insulin pump therapy allows for basal rate adjustments to influence insulin delivery.
• Exercise impacts glucose and insulin dynamics, necessitating tailored management strategies.

Purpose of the Study:

• To investigate the effect of reduced insulin pump basal rates on circulating free insulin and glucose levels before and during exercise.
• To compare the impact of exercise versus rest on these metabolic parameters following basal rate reduction.

Main Methods:

• An open-label, randomized crossover study involving 14 adults with type 1 diabetes on insulin pump therapy.
• Participants underwent two stages: exercise and rest, after overnight basal insulin delivery was halved.
• Plasma free insulin and glucose were measured over several hours, comparing exercise to rest conditions.

Main Results:

• Halving basal insulin 1 hour prior to exercise did not significantly lower circulating free insulin at exercise onset.
• Exercise transiently increased free insulin levels compared to rest.
• Hypoglycemia occurred in some participants with low-normal baseline glucose, indicating basal reduction alone was insufficient.

Conclusions:

• Insulin basal rate reduction alone is inadequate for preventing exercise-induced hypoglycemia in type 1 diabetes.
• Greater basal rate reduction and/or carbohydrate supplementation may be necessary.
• Exercise can transiently increase insulin levels, complicating management after basal rate adjustments.