Ambulatory Glucose Profile According to Different Phases of the Menstrual Cycle in Women Living With Type 1 Diabetes

Context: Some women living with type 1 diabetes complain of changes in glucose values according to the different phases of menstruation. Objective: To evaluate this variability through continuous glucose monitoring (CGM) data in type 1 diabetes patients. Design: Observational study. Setting: Ambulatory data, recruitment in 2 centers in the Paris region. Patients: Twenty-four women with type 1 diabetes having spontaneous menstrual cycles. Intervention: Collection of CGM data for 62 spontaneous menstrual cycles, with evaluation of five 3-day phases during each cycle: (1) early follicular (menstruations), (2) mid-follicular, (3) peri-ovulatory, (4) mid-luteal, and (5) late luteal. Main outcome measure: Time in range (TIR, prespecified). Results: TIR decreased for each consecutive phase (61 [+ or -] 18%; 59 [+ or -] 18%; 59 [+ or -] 20%; 57 [+ or -] 18%; and 55 [+ or -] 20%, P = 0.02). The linear mixed model highlighted a decrease in TIR in the mid-luteal (P = 0.03) and late luteal (P < 0.001) phases compared with the early follicular phase. Time above range was significantly higher during the late luteal phase than the early follicular phase (P = 0.003). Time below range was significantly higher during the mid-follicular phase than in the early follicular phase. Conclusion. In most of the study population, glucose levels rose linearly throughout the menstrual cycle, reaching a maximum in the late luteal phase. A sharp decrease was seen for most participants at the beginning of menstrual bleeding. This should be taken into consideration in daily care of type 1 diabetes patients to avoid hypoglycemia. Key Words: type 1 diabetes, menstrual cycle, glycemic variability, continuous glucose monitoring, time in range Abbreviations: CGM, continuous glucose monitoring; CV, coefficient of variation; HBGI, high blood glucose index; ICC, interclass correlation coefficient; LBGI, low blood glucose index; T1D, type 1 diabetes; TAR, time above range; TBR, time below range; TIR, time in range.