ADJUnct Semaglutide Treatment in Type 1 Diabetes

Prior treatment

• Current use (≥ 2 weeks of continuous use) of any steroidal medication, or anticipated long-term steroidal treatment (\>4 weeks continuously), during the study period
• Use of GLP-1RA or weight loss medications in the past 3 month
• Planning for bariatric surgery during the study period
• History of severe hypoglycemia in the previous 3 months
• Have a pacemaker, metal implants, or aneurysm clips or weigh \>330 lbs (exclusion only if doing MRI)
• Use of investigational drugs within 5 half-lives prior to screening

Other illness

• Clinical diagnosis/history of gastroparesis or gastric motility disorders
• History of diabetic ketoacidosis requiring hospitalization in the past 3 months
• History of allergy to any form of insulin, GLP-1RA or its excipients
• History of any form of pancreatitis
• History of stroke, myocardial infarction in the past 3 months
• History of congestive heart failure class III or IV
• History of acute or chronic liver disease
• History of malignancy requiring chemotherapy, surgery or radiation in previous 5 years
• Personal or family history of multiple endocrine neoplasia type 2 (MEN-2) or familial thyroid carcinoma or non-familial medullary thyroid carcinoma
• Any comorbidities or medical conditions such as severe psychiatric disorder that make a person unfit for the study at the discretion of the investigators

Lab values

• HbA1c ≤7.0 % or ≥ 10.0% at screening
• Patients with T1D using any glucose lowering medications other than insulin at the time of screening
• Serum triglycerides \>500 mg/dL
• eGFR below 45 ml/min/1.73 m\^2 using CKD-EPI formula

Age

• Age \<18 years and \>65 years
• Women of childbearing age wanting to become pregnant

Other

• Less than 12 months of insulin treatment
• Use of unapproved insulin for HCL system. E.g. use of Fiasp in the Tandem Control-IQ system
• Not willing to share the devices (HCL system) data uploads
• Non compatible devices (e.g. pump, CGM or smart phones) for data transfer
• Current use of multiple daily injection or inhaled insulin (Afrezza)
• Pregnancy, breast feeding, and positive pregnancy test during screening
• Unwilling to use acceptable contraceptive methods (for both men and women) during the trial period
• Participation to other intervention trials during the study period

• For an eligible subject, all inclusion criteria must be answered "yes"
• Age ≥18 and ≤ 65 years
• Patients with clinical diagnosis of T1D diagnosed for at least 12 months
• Patient is on FDA- approved hybrid closed-loop system for ≥ 3 months
• Willing to use once weekly semaglutide
• Willing to share devices (HCL system) data uploads
• HbA1c \>7.0% and \<10.0%
• Body mass index ≥30 kg/m2
• Has current glucagon product to treat severe hypoglycemia
• Has current ketone meters to check ketones
• Ability to provide informed consent before any trial-related activities