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Active, Not Recruiting

NCT Number: NCT07478211

Menstrual Cycle Mapping While Using Closed-Loop Insulin Delivery

The hypothesis is that menstrual cyclicity affects glucose and energy metabolism in women with type 1 diabetes. The rationale of the hypothesis on cycle effects builds on the assumption that fluctuations of female sex hormones across the menstrual cycle cause changes in physiological parameters of glucose metabolism and energy homeostasis and/or lifestyle aspects involved in the regulation of blood glucose and body weight. It is expected that hormone fluctuations affect insulin sensitivity, gastric emptying, eating behaviour and energy expenditure. It is anticipated that insulin sensitivity is highest in the pre-ovulatory phase and lowest in the mid-luteal phase. It is further expected that gastric emptying peaks in the follicular phase, and highest energy expenditure and dietary intake are expected during the mid-luteal phase.

The primary objective of this study is to characterize glucose and energy metabolism throughout the menstrual cycle in natural cycling women with type 1 diabetes. Further objectives are to assess the impact of the menstrual cycle on glucose control and insulin requirements, investigate how fluctuations in sex hormone levels influence glucose and energy metabolism, and quantify both inter- and intra-individual variability in metabolic changes related to the menstrual cycle. Additionally, the study will evaluate whether changes in key physiological components of glucose metabolism and behavioural factors mediate menstrual cycle-related variations in glucose control and insulin requirements.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

Key information

Conditions

Diabetes Mellitus, Type 1 Autoimmune Diseases Diabetes Mellitus Endocrine System Diseases Energy Metabolism Glucose Metabolism Disorders Immune System Diseases Metabolic Diseases Nutritional and Metabolic Diseases

Age range

18 year–45 year

Sex eligibility

Female

Study type

Observational

Primary location

Department of Diabetes, Endocrinology, Nutritional Medicine and Metabolism (UDEM), Inselspital, Bern University Hospital

Bern, Canton of Bern, 3010, Switzerland

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Female sex assigned at birth
  • Type 1 diabetes for at least 12 months
  • Aged 18-45 years
  • Natural menstrual cycle (occurring without medical or hormonal interventions)
  • Functional insulin therapy delivered via injection or insulin pump
  • Willingness to follow study-related procedures
  • Willingness to use mechanical contraception during the time of study participation

Exclusion criteria

  • Use of contraceptives or medical interventions that interfere with natural hormonal fluctuations of the menstrual cycle or cyclical bleeding
  • Interventions interfering with glucose or energy metabolism (other than insulin, thyroid hormone replacement or statins), as judged by the investigator, will be paused for the duration of the study, with an adequate washout duration prior to the start of data collection
  • Presence of any physical or psychological condition, or any medical intervention likely to interfere with the conduct of the procedures and/or their evaluation, as judged by the investigator
  • Pregnant or breast-feeding
  • Participation in another clinical study that interferes with the interpretation of the study results as judged by the investigator

Treatment and study plan

Primary outcomes

  1. Time in target glucose range

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    The primary metric for glucose control is the proportion of time with sensor glucose levels in the target range (3.9-10mmol/L, %).

    Glucose levels will be measured using a continuous glucose monitoring sensor (Dexcom G6 or an equivalent CGM sensor).

Secondary outcomes

  1. Algorithm-directed insulin delivery following a standardized meal

    Time frame: The outcome will be measured at each standardized meal assessment, performed during the three key menstrual cycle phases (early-follicular, pre-ovulatory, and mid-luteal),across three menstrual cycles, resulting in a total of nine 3-hour assessment times

    The primary insulin metric is the algorithm-directed insulin dose (units) delivered over a 3 hour period following a standardized meal without a manual bolus. Insulin delivery is recorded using the mylife CamAPS FX automated insulin delivery system.

  2. Insulin sensitivity

    Time frame: Continuously over three menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Insulin sensitivity will be estimated continuously throughout the study from sensor glucose and insulin pump data, collected via the mylife CamAPS FX automated insulin delivery system, using mathematical modeling.

  3. Gastric emptying

    Time frame: The outcome is evaluated at each phase-specific assessment (early follicular, pre-ovulatory, and luteal) for one menstrual cycle.

    This outcome is based in the [13C]-acetate breath test. Breath 13CO2 enrichment is analyzed using infrared spectrometry and kinetics parameters are derived using mathematical modelling. The main parameter of interest is T50 (ie., the time until half of the ingested meal was absorbed).

    This outcome is measured only in a subgroup of 15 participants.

  4. Total energy expenditure

    Time frame: Continuously over one menstrual cycle. Duration varies depending on individual cycle length, ranging from 20 days to 50 days.

    Total energy expenditure will be quantified using the doubly labelled water method. This outcome is measured only in a subgroup of 15 participants.

  5. Substrate oxidation

    Time frame: Assessed once at each phase-specific assessment (early follicular, pre-ovulatory, and luteal) for one menstrual cycle

    Substrate oxidation (i.e, quantified by the relative contribution of fat oxidation to resting energy expenditure) will be measured by indirect calorimetry in the fasted state (≥8 hours) to provide additional context as a physiological determinant of glucose and energy metabolism. This outcome is measured only in a subgroup of 15 participants.

  6. Dietary intake

    Time frame: Measured for 3 days following each phase-specific assessment (early follicular, pre-ovulatory, and luteal) across three menstrual cycles, totaling 27 days over 3 cycles

    Total energy intake (kcal/day) will be assessed by recording all meals using an image-based automated food analysis application SNAQ.

  7. Physical activity

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    The number of steps per day, as a component of physical activity, will be measured using the Garmin Venu 3 smartwatch.

Other outcomes

  1. Postprandial mean glucose

    Time frame: The outcome will be evaluated continuously over 3 menstrual cycles (duration varies from 60 days (20-day cycles) to 150 days (50-day cycles)) as well as at each standardized meal assessment, resulting in a total of nine 3-hour assessment times.

    Mean postprandial glucose levels measured using continuous glucose monitoring in the 3 hours following meals. Meal timepoints defined as manual carbohydrate entries in the mylife CamAPS FX automated insulin delivery system. This outcome serves as an additional metric within the overall assessment of glucose control. Additionally, mean postprandial glucose levels will be specifically measured in the 3 hours following the standardized meal assessment using continuous glucose monitoring.

  2. Postprandial peak glucose

    Time frame: The outcome will be evaluated continuously over 3 menstrual cycles (duration varies from 60 days (20-day cycles) to 150 days (50-day cycles)) as well as once for each standardized meal assessment (9 values in total).

    Peak postprandial glucose levels measured using continuous glucose monitoring in the 3 hours following meals. Meal timepoints defined as manual carbohydrate entries in the mylife CamAPS FX automated insulin delivery system. This outcome serves as an additional metric within the overall assessment of glucose control. Additionally, peak postprandial glucose levels will be specifically measuredin the 3 hours following the standardized meal assessment using continuous glucose monitoring.

  3. Proportion of time spent in the hyperglycaemic range

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles)

    Glucose levels above 10 mmol/L are classified as hyperglycaemic. Glucose levels will be measured using a continuous glucose monitoring (Dexcom G6 system or an equivalent CGM sensor).

    This outcome serves as an additional metric within the overall assessment of glucose control.

  4. Proportion of time spent in hypoglycaemic range

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Glucose levels below 3.9 mmol/L are classified as hypoglycaemic. Glucose levels will be measured using continuous glucose monitoring (Dexcom G6 system or an equivalent CGM sensor) This outcome serves as an additional metric within the overall assessment of glucose control.

  5. Glucose variability - standard deviation

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Glucose variability assessed as the standard deviation (SD) of sensor glucose values measured using continuous glucose monitoring.

    This outcome provides an additional metric contributing to the assessment of glucose variability and overall glucose control.

  6. Glucose variability - coefficient of variation

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Glucose variability assessed as the coefficient of variation (CV) of sensor glucose values measured using continuous glucose monitoring data.

    This outcome provides an additional metric contributing to the assessment of glucose variability and overall glucose control.

  7. Glucose variability - mean amplitude of glycaemic excursions

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Glucose variability assessed as the mean amplitude of glycaemic excursions (MAGE) derived from continuous glucose monitoring data.

    This outcome provides an additional metric contributing to the assessment of glucose variability and overall glucose control.

  8. Total daily insulin dose

    Time frame: Over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Total daily insulin dose (U/day) will be evaluated using the mylife CamAPS FX automated insulin delivery system, which includes a continuous glucose monitoring sensor (Dexcom G6 or an equivalent CGM sensor for participants already using mylife CamAPS FX with a different sensor), an insulin pump (YpsoPump), and the CamAPS FX application. This outcome serves as an additional measure of individual insulin requirements.

  9. Basal insulin

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    As an additional measure of insulin requirements, the proportion of basal insulin relative to total insulin delivery (%) will be assessed.

    It will be measured using the mylife CamAPS FX AID system consisting of a continuous glucose monitoring sensor (Dexcom G6 system or an equivalent CGM sensor if they already use the mylife CamAPS FX AID system with a different sensor), the insuline pump (Ypsopump) and the CamAPS FX app.

  10. Bolus frequency

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Units are (n/day). The outcome is the number of manual boluses entered into the mylife CamAPS FX AID system.

  11. Resting energy expenditure

    Time frame: Assessed once at each phase-specific assessment (early follicular, pre-ovulatory, and luteal) for one menstrual cycle.

    Resting energy expenditure (kcal/day) will be measured by indirect calorimetry in the fasted state (≥8 hours) to provide additional context as a physiological determinant of energy metabolism. This outcome is measured only in a subgroup of 15 participants.

  12. Model-estimated energy intake

    Time frame: Continuously over three menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Daily energy intake (kcal/day) will be estimated using an energy balance model based on frequently measured body weight and physical activity data, and, where available, energy expenditure assessed using the doubly labeled water methodology. This outcome provides a complementary, model-based estimate of energy intake alongside self-reported dietary intake.

  13. Proportion of carbohydrate intake

    Time frame: Measured over 3 days following each phase-specific assessment (early follicular, pre-ovulatory, and luteal) across three menstrual cycles, totaling 27 days from 9 assessments.

    The proportion of carbohydrate intake (% of total energy intake) will be derived from meal records collected using the image-based automated food analysis application (SNAQ), providing complementary information on macronutrient distribution.

  14. Proportion of fat intake

    Time frame: Measured over 3 days following each phase-specific assessment (early follicular, pre-ovulatory, and luteal) across three menstrual cycles, totaling 27 days from 9 assessments.

    The proportion of fat intake (% of total energy intake) will be derived from meal records collected using the image-based automated food analysis application (SNAQ), providing complementary information on macronutrient distribution.

  15. Proportion of protein intake

    Time frame: Measured over 3 days following each phase-specific assessment (early follicular, pre-ovulatory, and luteal) across three menstrual cycles, totaling 27 days from 9 assessments.

    The proportion of protein intake (% of total energy intake) will be derived from meal records collected using the image-based automated food analysis application (SNAQ), providing complementary information on macronutrient distribution.

  16. Dietary fiber intake

    Time frame: Total intake over 3 days following each phase-specific assessment (early follicular, pre-ovulatory, and luteal) across three menstrual cycles, totaling 27 days from 9 assessments.

    Dietary fiber intake will be derived from meal records collected using the SNAQ application as an additional component of overall dietary intake assessment.

  17. Food category distribution

    Time frame: Measured continuously at every meal for 3 days following each phase-specific assessment (early follicular, pre-ovulatory, and luteal) across three menstrual cycles, totaling 27 days from 9 assessments.

    Food category distribution will be derived from meal records collected using the SNAQ application, providing complementary information on dietary patterns within overall dietary intake.

  18. Activity minutes per day

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Active minutes per day will be measured using the Garmin Venu 3 smartwatch as a complementary indicator of physical activity.

  19. Body weight

    Time frame: Measured daily over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Body weight will be measured using the Garmin Index S2 smart scale to provide additional metabolic context.

  20. Fat mass

    Time frame: Daily over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Percentage of body fat mass, as a component of body composition, will be measured using the Garmin Index S2 smart scale to provide additional metabolic context.

  21. Fat-free mass

    Time frame: Measured daily over three menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Percentage of fat-free mass, as a component of body composition, will be measured using the Garmin Index S2 smart scale to provide additional metabolic context.

  22. Beta-hydroxybutyrate levels

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Beta-hydroxybutyrate levels (mmol/L), will be assessed using the SiBio Ketone Sensor to provide additional metabolic context.

  23. Heart rate

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Heart rate (bpm), will be assessed using the Garmin Venu 3 smartwatch to provide a broader metabolic context.

  24. Heart rate variability

    Time frame: Continuously over 3 menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Heart rate variability (High and low frequency components or equivalent time domain indices), will be assessed using the Garmin Venu 3 smartwatch to provide a broader metabolic context and as an indicator of autonomic nervous system activity.

  25. Patient-reported perceived impact

    Time frame: At study completion (after three menstrual cycles).

    Perceived impact of the menstrual cycle on diabetes control and management will be captured retrospectively at the end of the study using an experience questionnaire.

  26. Patient-reported perceived impact - real-time electronic logs

    Time frame: Continuously over three menstrual cycles. Duration varies depending on individual cycle length, ranging from 60 days (20-day cycles) to 150 days (50-day cycles).

    Perceived impact of the menstrual cycle on diabetes control and management will be captured additionally in real time using electronic logs in a smartphone app. Data are considered supplementary to the experience questionnaire-based assessment.

Sponsors and collaborators

Lead sponsor

Lia Bally

Other

Collaborators

  • Bangerter Foundation and Swiss Academy of Medical Science
  • Bern Medtech Collaboration Call
  • Burgergemeinde
  • CSEM Centre Suisse d'Electronique et de Microtechnique SA - Recherche et Developpement
  • DexCom, Inc.
  • Fresenius Kabi (Schweiz) AG
  • Gertrud and Walter Siegenthaler Foundation
  • Innosuisse - Swiss Innovation Agency
  • Insel Gruppe AG, University Hospital Bern
  • University of Bern
  • mylife Diabetes Care AG

Registry information

Acronym: MCM-Loop

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Mar 17, 2026
Registry last updated
Jun 2, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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