Phases of Menstrual Cycle May Influence Glucose Control in Type 1 Diabetes: Study
Switzerland: Real-world data show that glycemic control, insulin sensitivity, and insulin requirements fluctuate across different phases of the menstrual cycle in women with type 1 diabetes. These phase-dependent changes highlight the importance of individualized glucose monitoring and insulin dose adjustments to optimize diabetes management throughout the menstrual cycle.
Hormonal changes during the menstrual cycle are known to affect glucose metabolism, but their impact in individuals using automated insulin delivery (AID) systems has not been well characterized. To address this gap, Stefanie Hossmann from the Diabetes Center Berne, Switzerland, and colleagues investigated how menstrual cycle phases influence insulin sensitivity, insulin requirements, and glycemic control in adults with type 1 diabetes using AID systems. The findings were published in Diabetes Care.
The decentralized observational study analyzed real-world data voluntarily contributed by menstruating adults with regular menstrual cycles who were using automated insulin delivery systems. Participants self-enrolled and shared anonymized continuous glucose monitoring (CGM) data, insulin delivery records, carbohydrate intake, and menstrual cycle information. The researchers compared glucose control and insulin requirements across different menstrual cycle phases and estimated insulin sensitivity using a hierarchical Bayesian state-space model based on CGM data.
Key findings from the study include:
- The analysis included 77 participants who contributed data from 380 menstrual cycles.
- Insulin requirements, carbohydrate intake, and glycemic outcomes varied consistently across menstrual cycle phases.
- Total daily insulin dose and carbohydrate intake were highest during the luteal phase.
- The luteal phase was also associated with higher average glucose levels and reduced time spent within the target glucose range.
- Insulin sensitivity was approximately 2.6% higher during the early follicular phase and 2.6% lower during the mid-luteal phase.
- Nearly 85% of participants followed the overall population trend, although considerable differences in individual responses were observed.
The findings suggest that hormonal fluctuations across the menstrual cycle continue to affect glucose regulation despite the use of automated insulin delivery systems. Although most participants showed similar phase-related trends, considerable individual variation underscored the need for personalized diabetes management.
The researchers noted that current diabetes guidelines and automated insulin delivery systems do not account for menstrual cycle–related physiological changes. Incorporating these predictable fluctuations into diabetes care could improve glycemic control and optimize insulin dosing for women with type 1 diabetes.
Overall, the study confirms that insulin sensitivity, insulin requirements, and glycemic control vary across menstrual cycle phases. The researchers called for future diabetes guidelines and next-generation automated insulin delivery systems to integrate sex-specific physiological changes to support more personalized diabetes management.
Reference:
Stefanie Hossmann, Maya Friedman, Aritz Lizoain, Madleina Caduff, Vincent Braunack-Mayer, Laura Burlando, Rayhan A. Lal, Eda Cengiz, Katarina Braune, Susanne Reger-Tan, Antje Knopf, Thomas Züger, Saira Khan-Gallo, Martina Rothenbühler; Effects of Menstrual Cycle on Insulin Sensitivity in Type 1 Diabetes: An Observational Study of Individuals Using an Automated Insulin Delivery System. Diabetes Care 2026; dc260692. https://doi.org/10.2337/dc26-0692
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