Impact of continuous moderate-intensity aerobic exercise on glycemic control according to different phases of the menstrual cycle in females with type 1 diabetes

Aim

To assess the effects of continuous moderate-intensity aerobic exercise (CONT) on glycemic control in women with type 1 diabetes (T1D) across different phases of the menstrual cycle.

Methods

Twenty-five women with T1D completed two 30-minute CONT sessions: one during the follicular phase and the other during the luteal phase. Glycemic control was assessed during exercise by plasma glucose analysis and at 24 h post-exercise by continuous glucose monitoring.

Results

A decline in blood glucose levels was observed after exercise, regardless of menstrual phase, from approximately 155 mg/dL to about 110 mg/dL. In the 24 h following exercise, the incidence of hypoglycemia was low (less than 2 %); in contrast, exercise in the luteal phase tended to increase hyperglycemia compared to the previous 24 h (from 38.2 % to 44.2 %), as well as compared to the follicular phase, with higher mean blood glucose levels observed.

Conclusion

CONT has an immediate glucose-lowering effect regardless of menstrual cycle phase. However, while in the follicular phase TIR remains stable, in the luteal phase, it declines, with a corresponding increase in hyperglycemia, supporting the idea that exercise-induced glucose regulation varies across menstrual phases, highlighting the potential need for insulin dose adjustments depending on the cycle’s phase.