Trajectories in Insulin Sensitivity Across MEnstrual cycleS in Women With Type 1 Diabetes

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