Effects of Menstrual Cycle on Insulin Sensitivity in Type 1 Diabetes: An Observational Study of Individuals Using an Automated Insulin Delivery System
Authors' conclusion
Our findings confirm phase-dependent variation in insulin needs, glycemic outcomes, and insulin sensitivity across the menstrual cycle and highlight that sex-specific physiology is an important factor in glycemic regulation that is not yet addressed by current guidelines and AID systems.
Study context
- Population
- Menstruating adults with T1D reporting regular menstrual cycles and using an automated insulin delivery (AID) system; self-enrolled, donated anonymized continuous glucose monitoring (CGM), insulin, carbohydrate and cycle data380 menstrual cycles
- Participants
- 77 adults
- Exposure
- Menstrual cycle phases
- Outcome
- Model-derived insulin sensitivity (population level)
Methodological detailsdecentralized, real-world data, hierarchical Bayesian state-space model
- Decentralized
- Real-world data
- Hierarchical Bayesian state-space model
Main finding
As reported in the abstract
Early follicular
+2.6%
CrI 0.3–5.0
Midluteal
−2.6%
CrI −5.2–-0.1
Observational data: associations, not effects.
Further findings
Insulin requirements, carbohydrate intake and glycemic outcomes across cycle phases
- Systematic variation across cycle phases
- Total daily insulin dose and carbohydrate intake peaked in the luteal phase, with higher mean glucose and reduced TIR
Individual patterns consistent with population-level trend
- Participants consistent with population-level trend
- 84.7%
- Substantial interindividual heterogeneity
Original publication
Effects of Menstrual Cycle on Insulin Sensitivity in Type 1 Diabetes: An Observational Study of Individuals Using an Automated Insulin Delivery System. Diabetes Care. Published 22 July 2026. doi:10.
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