Fear of hypoglycemia is a major barrier to exercise in people with type 1 diabetes (T1D) . Females with T1D tend to be less active than males with T1D, which might be due to significant knowledge gaps around blood glucose responses to exercise, especially with regards to the menstrual cycle. We compared the effect of a moderate aerobic exercise (cycling at 50% of pre-determined VO2peak for 45 min) on glycemic responses between the early follicular and late luteal phases of the menstrual cycle in 9 female participants with T1D (mean±SD: age 30.2±9 years, A1C 7.4±0.7%, VO2peak32.5±4.2 mL/kg/min) with regular menstrual cycles not using oral contraceptives. In both phases, serum glucose decreased from pre to post exercise and increased throughout the 60-min recovery (effect of time p<0.05) but was not significantly different between the two phases (effect of phase p>0.05) . Serum insulin (log transformed) decreased from pre to post exercise in both phases (effect of time p<0.05) but was not significantly different between the two phases (effect of phase p>0.05) . The number of participants needing glucose supplementation (Dex4) to prevent hypoglycemia before and during exercise and recovery was significantly higher in the luteal versus the follicular phase (6/9 vs. 1/9, Fisher’s p=0.049) . Continuous glucose monitoring, however, showed no increase in the number of hypoglycemic episodes post exercise during the luteal phase. There were more post-exercise hyperglycemic episodes in the follicular versus the luteal phase (3±0.5 vs. 1.3±0.3, p=0.029) . These data suggest that females with T1D may be more prone to post-exercise hyperglycemia during the follicular phase, while needing more glucose supplementation to prevent hypoglycemia during the luteal phase of the menstrual cycle. These data should help guide recommendations for carbohydrate and insulin adjustment.
Z.Momeni: None. J.E.Yardley: Research Support; Abbott, Dexcom, Inc., LifeScan, Speaker's Bureau; Abbott Diabetes.