Glycemic control may differ throughout the menstrual cycle, with increased incidence of hyperglycemia in the luteal phase. However, it is unclear if glycemic differences exist in the follicular vs. luteal phase during prolonged fasted exercise in T1D. The aim of this study was to determine if the early follicular vs. luteal phase impacts blood glucose levels during and post-exercise.

Females with T1D (n = 7, age 28±6 years, A1c 6.9±0.6%) completed two 2-hr aerobic exercise sessions (∼45% VO2peak), during the luteal (days 18-24) and early-follicular phases (days 1-6) of menstruation. Carbohydrate (CHO) intake (0.3g/kg/hr) occurred every 30-min if glucose was between 72-180 mg/dL.

No differences existed between the two phases for starting glucose, changes in glucose, CHO consumption and CHO oxidation during exercise (Table). Baseline glucagon was elevated in the luteal (28±25pg/mL) vs. follicular phase (13±12pg/mL; P<0.05). Following exercise, overnight time in hyperglycemia (>180 mg/dL) was greater in the luteal (59±44%) vs. follicular phase (21±30%; P<0.05).

Overall, glycemic responses during prolonged fasting exercise are similar between luteal and follicular phases in women with T1D, as are CHO intake needs. However, after exercise in the luteal phase, glycemia tends to be elevated and appears to contribute to greater time in hyperglycemia.


S.M. McGaugh: None. D. Zaharieva: Speaker’s Bureau; Self; Ascensia Diabetes Care, Insulet Corporation, Medtronic. R. Pooni: None. N.C. D’Souza: None. J.E. Yardley: Research Support; Self; Abbott, Dexcom, Inc., LifeScan Canada. Speaker’s Bureau; Self; Dexcom, Inc. M. Riddell: Advisory Panel; Self; Zucara Therapeutics Inc. Consultant; Self; Lilly Diabetes. Research Support; Self; Dexcom, Inc., Insulet Corporation. Speaker’s Bureau; Self; Medtronic, Novo Nordisk A/S.

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