Impact of an Advanced Hybrid Closed-Loop System on Glycemic Control Throughout the Menstrual Cycle in Women with Type 1 Diabetes Prone to Hypoglycemia.

This study aimed to evaluate the impact of advanced hybrid closed loop (AHCL) on glycemic control throughout the menstrual cycle (MC) in women with type 1 diabetes. We included 39 pairs of spontaneous MCs from 13 participants, before and after switching from sensor-augmented pump to AHCL. Baseline time below range <70 mg/dL (TBR <70) was significantly higher during the midfollicular phase than during late luteal phase (5.7% ± 5.0% vs. 4.1% ± 3.0%), but similar time in range 70-180 mg/dL (TIR) was observed throughout the MC. After switching to AHCL, a reduction in TBR <70 and an increase in TIR were observed in all phases. Phase-dependent changes in insulin infusion were detected and pre-existing differences in TBR <70 were eradicated (3.5% ± 3.2% vs. 3.0% ± 3.0%). However, TIR became significantly higher during the early follicular phase than during the late luteal phase (79.1% ± 9.3% vs. 74.5% ± 10.0%). In conclusion, AHCL improved glycemic control throughout the MC, but performance differed according to phase.