Glycemic Variations During the Menstrual Cycle in Women With Type 1 Diabetes

Inclusion Criteria:

1. Females aged 18 to 50 living in Canada.

2. Clinical diagnosis of type 1 diabetes or latent autoimmune diabetes in adults (LADA)for at least one year.

3. Using insulin pump therapy, multiple daily injections or automated insulin deliverysystems for at least 3 months.

4. Using a continuous glucose monitoring (CGM) system.

5. Having at least one menses in the last 40 days.

6. Accepting to share CGM data with the research team and if applicable insulin pumpdata.This access will be limited to the study period.

7. Having a smartphone or tablet to follow menstrual cycles.

8. Stable weight (less than 5% variation in the last 3 months).

Exclusion Criteria:

1. Using a hormonal contraception method that eliminates menses (Depo Provera,progestin intrauterine device, extented-cycle regimen with birth control pill)

2. Using regular insulin (Entuzity U500, Novolin ge Toronto or Humulin R).

3. Clinically significant nephropathy (eGFR < 30 ml/min/1.73m2, planned or on dialysis)or neuropathy (e.g., known uncontrolled gastroparesis) as judged by theinvestigator.

4. Recent (< 6 months) acute macrovascular event (e.g., acute coronary syndrome orcardiac surgery).

5. Anticipated therapeutic change (including change of insulin type and/or type of CGMsensor, insulin pump or AID (automated insulin device) system) between admission andend of the study.

6. Anticipated change in contraception method or plan to begin or stop a contraceptivemethod.

7. Anticipated need to use acetaminophen during the study period at a dose above 1gevery 6 hours.

8. Pregnancy (ongoing or current attempt to become pregnant)

9. Breastfeeding

10. Uncontrolled thyroid disease (TSH should be in target range and treatment stable forat least 6 weeks).

11. Severe hypoglycemic episode within two weeks of screening

12. Severe hyperglycemic episodes requiring hospitalization in the last 3 months.

13. Current use of glucocorticoid medication (except low stable dose and inhaledsteroids and stable adrenal insufficiency treatment e.g., Cortef®)

14. Agents affecting gastric emptying (Motilium®, Victoza®, Ozempic®, Trulicity®,Byetta® and Symlin®) as well as oral anti-diabetic agents (Metformin, Prandase®,DPP-4 inhibitors) unless at a stable dose for 3 months and without anticipatedchange during the study.

15. Current use of SGLT-2 inhibitors unless at a stable dose for at least 3 months,without anticipated change during the study and appropriate ketone testing isperformed.

16. Other serious medical illnesses which likely interfere with study participation orwith the ability to complete the study by the judgment of the investigator.

17. Anticipation of a significant change in exercise or diet regimen between admissionand end of the study (i.e., starting or stopping an organized sport; plannedsignificant diet change).

18. Anticipated radiologic examination incompatible with CGM wear for more than 10 daysbetween admission and end of the study (e.g., repeated MRI).

19. In the opinion of the investigator, a participant who is unable or unwilling tocomplete the study.

20. If taking medication for hypothyroidism, no change of dose (Levothyroxin) in thelast 6 weeks.