ADJUnct Semaglutide Treatment in Type 1 Diabetes

Inclusion Criteria:

For an eligible subject, all inclusion criteria must be answered "yes"

1. Age ≥18 and ≤ 65 years

2. Patients with clinical diagnosis of T1D diagnosed for at least 12 months

3. Patient is on FDA- approved hybrid closed-loop system for ≥ 3 months

4. Willing to use once weekly semaglutide

5. Willing to share devices (HCL system) data uploads

6. HbA1c >7.0% and <10.0%

7. Body mass index ≥30 kg/m2

8. Has current glucagon product to treat severe hypoglycemia

9. Has current ketone meters to check ketones

10. Ability to provide informed consent before any trial-related activities

Exclusion Criteria:

1. Age <18 years and >65 years

2. HbA1c ≤7.0 % or ≥ 10.0% at screening

3. Less than 12 months of insulin treatment

4. Use of unapproved insulin for HCL system. E.g. use of Fiasp in the Tandem Control-IQsystem

5. Not willing to share the devices (HCL system) data uploads

6. Non compatible devices (e.g. pump, CGM or smart phones) for data transfer

7. Current use of multiple daily injection or inhaled insulin (Afrezza)

8. Patients with T1D using any glucose lowering medications other than insulin at thetime of screening

9. Pregnancy, breast feeding, and positive pregnancy test during screening

10. Women of childbearing age wanting to become pregnant

11. Unwilling to use acceptable contraceptive methods (for both men and women) duringthe trial period

12. Current use (≥ 2 weeks of continuous use) of any steroidal medication, oranticipated long-term steroidal treatment (>4 weeks continuously), during the studyperiod

13. Use of GLP-1RA or weight loss medications in the past 3 month

14. Clinical diagnosis/history of gastroparesis or gastric motility disorders

15. Serum triglycerides >500 mg/dL

16. Planning for bariatric surgery during the study period

17. eGFR below 45 ml/min/1.73 m^2 using CKD-EPI formula

18. History of severe hypoglycemia in the previous 3 months

19. History of diabetic ketoacidosis requiring hospitalization in the past 3 months

20. History of allergy to any form of insulin, GLP-1RA or its excipients

21. History of any form of pancreatitis

22. History of stroke, myocardial infarction in the past 3 months

23. History of congestive heart failure class III or IV

24. History of acute or chronic liver disease

25. History of malignancy requiring chemotherapy, surgery or radiation in previous 5years

26. Personal or family history of multiple endocrine neoplasia type 2 (MEN-2) orfamilial thyroid carcinoma or non-familial medullary thyroid carcinoma

27. Have a pacemaker, metal implants, or aneurysm clips or weigh >330 lbs (exclusiononly if doing MRI)

28. Use of investigational drugs within 5 half-lives prior to screening

29. Participation to other intervention trials during the study period

30. Any comorbidities or medical conditions such as severe psychiatric disorder thatmake a person unfit for the study at the discretion of the investigators