An Observational Study on the Impact of Menstrual Cycle Phases on Carbohydrate Intake, Insulin Delivery and Glycaemia in Women With Type 1 Diabetes Using MiniMed 780G Automated Insulin Delivery System
Authors' conclusion
Menstrual cycle phase is associated with significant changes in carbohydrate intake, insulin delivery and TIR in women using MiniMed 780G. Despite increased insulin delivery, TIR was lower in the luteal phase, suggesting partial adaptation to menstrual cycle-related physiological changes.
Study context
- Population
- Women with T1D using the MiniMed 780G AID system; mean age 35.9 years, BMI 23.3 kg/m², HbA1c 50.8 mmol/mol [6.8%]118 cycles
- Participants
- 15 women
- Exposure
- Pre-menses week vs menses week (Method 1); five physiological phases vs mid-follicular (Method 2)
- Outcome
- Carbohydrate intake, insulin delivery and TIR (Method 1)
Methodological detailslinear mixed-effects models with random intercepts for participant and cycle, CGM and insulin delivery data retrieved from the CareLink portal
- Linear mixed-effects models with random intercepts for participant and cycle
- CGM and insulin delivery data retrieved from the CareLink portal
Main finding
As reported in the abstract
- Pre-menses week
- β (carbohydrate intake) +0.164 g kg-1; adjusted p = 0.003
- Pre-menses week
- β (total daily bolus) +0.018 U kg-1; adjusted p = 0.001
- Pre-menses week
- β (total daily basal) +0.011 U kg-1; adjusted p = 0.003
- Pre-menses week
- β (total daily dose) +0.029 U kg-1; adjusted p < 0.001
- Pre-menses week
- β (time in range (TIR)) −3.487 percentage points; adjusted p < 0.001
Observational data: associations, not effects.
Further findings
| Outcome | β (TIR) (percentage points) | P value |
|---|---|---|
| Insulin delivery and TIR by physiological phase (Method 2, reference mid-follicular)Mid luteal vs Mid-follicular | −3.34 | adjusted p = 0.007 |
Insulin delivery and TIR by physiological phase (Method 2, reference mid-follicular)
- Total daily basal and total daily dose significantly higher in the late luteal phase
Original publication
An Observational Study on the Impact of Menstrual Cycle Phases on Carbohydrate Intake, Insulin Delivery and Glycaemia in Women With Type 1 Diabetes Using MiniMed 780G Automated Insulin Delivery System. Diabetes Obes Metab. Published 17 August 2026. doi:10.
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