Standardized longitudinal data collection of diabetes management relevant factors in women with T1D (insulin requirements, glucose variability, nutritional information, and menstrual cycle information) to identify categories of cycle trajectories.

Inclusion criteria:

• Female sex
• Between 18 and 40 years at inclusion
• Menarche at least one year prior to study inclusion
• Regular menstrual cycle (at least one menstrual cycle in the last 40 days)
• Average menstrual cycle length between 21 and 38 days
• Difference in length between consecutive menstrual cycles of at most 7 days
• Living with type 1 diabetes or latent autoimmune diabetes in adults (LADA) for at least one year
• Actively using an AID system for their diabetes management at least six months prior to study inclusion

Exclusion criteria:

• Regular hormonal intake (e.g. corticosteroids), except: insulin, stable thyroid substitution, and hormonal contraception
• Pregnancy until two months postpartum (ongoing or planned)
• Current breastfeeding (including pumping), as well as two months following complete cessation of breastfeeding and pumping
• Known Polycystic Ovary Syndrome (PCOS)
• Intake of glucocorticoid medication, agents affecting gastric emptying, oral anti-diabetic agents (Metformin) or SGLT-2 inhibitors or GLP-1-analogs
• Individuals with work patterns involving frequent shifts between night and day work (e.g., alternating night and day shifts on a weekly or similar basis).
• Participation in an interventional study within two months preceding and during the present study

People with menstrual cycles living with Type 1 Diabetes who are using a hybrid closed-loop system.

We plan to share the data but haven't specified the details yet.