Effects of Menstrual Cycle on Insulin Sensitivity in Type 1 Diabetes: An Observational Study of Individuals…

Cohort studyDiabetes care· Jul 2026

Effects of Menstrual Cycle on Insulin Sensitivity in Type 1 Diabetes: An Observational Study of Individuals Using an Automated Insulin Delivery System.

Stefanie Hossmann, Maya Friedman, Aritz Lizoain … Martina Rothenbühler

EndocrinologyCohort studyClinical practiceQ1IF 15.8

Insulin sensitivity is greater in early follicular phase than midluteal phase.

Effects of Menstrual Cycle on Insulin Sensitivity in Type 1 Diabetes: An Observational Study of Individuals Using an Automated Insulin Delivery System.

Stefanie Hossmann … Martina Rothenbühler

Diabetes care · Jul 2026 · Q1 in Internal Medicine

Background

In menstruating individuals with type 1 diabetes, hormonal fluctuations across the menstrual cycle may alter insulin sensitivity and glycemia, despite advances in automated insulin delivery (automated insulin delivery) systems.

Purpose

This study aimed to characterize glycemic patterns, insulin requirements, and insulin sensitivity across menstrual cycle phases.

Methods

Self-enrolled and contributed anonymized continuous glucose monitoring (continuous glucose monitoring), insulin delivery, carbohydrate intake, and menstrual cycle data.

Results

insulin sensitivity was higher in the early follicular phase compared to the midluteal phase

MD 2.60 (95% CI 0.30 to 5)

null 0

0.30

5

CI excludes the null - significant

More results

Seventy-seven individuals contributed 380 menstrual cycles.

Insulin requirements, carbohydrate intake, and glycemic outcomes showed systematic variation across cycle phases.

Total daily insulin dose and carbohydrate intake peaked during the luteal phase, accompanied by higher mean glucose and reduced time in range.

More results

Although 84.7% of participants showed patterns consistent with the population-level trend, substantial interindividual heterogeneity was observed.

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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 automated insulin delivery systems.

Effects of Menstrual Cycle on Insulin Sensitivity in Type 1 Diabetes: An Observational Study of Individuals Using an Automated Insulin Delivery System.

Effects of Menstrual Cycle on Insulin Sensitivity in Type 1 Diabetes: An Observational Study of Individuals Using an Automated Insulin Delivery System.

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