Lean Mass Changes With Semaglutide in Adults With Type 1 Diabetes and Overweight/Obesity.

Inclusion Criteria: * Age 18-65 years old * Clinical diagnosis of T1D (type 1 diabetes) for ≥ 1 year, as per clinician judgement. * BMI (Body mass index) ≥ 27 kg/m2 * Use of multi-daily injections or insulin pump therapy. * Use of CGM (continuous glucose monitoring). * Agreement to the use of a highly effective method of birth control in persons of child-bearing age (if sexually active) and active avoidance of pregnancy during the trial. Child-bearing potential refers to participants of the female sex post-menarche who have not reached menopause or have a disclosed medical condition causing sterility (e.g. hysterectomy). Post-menopausal state refers to the absence of menses for 12 months without any alternative cause. * Diabetic retinopathy assessment performed within the last 2 years, as per participant history. Exclusion Criteria: * Pre-existing conditions limiting physical activity, specifically inability to walk for 6 minutes. * Active proliferative diabetic retinopathy requiring surgery or laser/injectable therapy within the last 3 months. \*If a history of proliferative retinopathy is present within the last year, written permission from the eligible participant's ophthalmologist or optometrist is required\* * HbA1c (glycated hemoglobin) ≥ 10% within the last 3 months. * Current use of non-insulin anti-hyperglycemic agents within the last month. * Severe hypoglycemic episode within the last 3 months, defined as an event where glycemia was \< 4 mmol/L, resulting in seizure, loss of consciousness, or need for third-party assistance in treatment. * Diabetic ketoacidosis (DKA) within the last 3 months (DKA refers to the need to present to medical attention and the requirement of intravenous insulin due to ketones) * History of bariatric surgery * Personal history of acute/chronic pancreatitis or gallstone disease without cholecystectomy. * Personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2. * Severe impairment of renal function with eGFR \<30 mL/min/1.73 m2 (using CKD-EPI formula), measured within the last 12 months. * Use of supraphysiological doses of glucocorticoids in the last 3 months, and/or expected use at some point in the next 6 months. * Planned or ongoing pregnancy * Breastfeeding individuals * Prior hypersensitivity reaction to GLP1-RA (glucagon-like-peptide-1 receptor agonist) * Clinically significant gastroparesis, defined as persistent symptoms despite pharmacotherapy such as domperidone. * Any prior diagnostic history of eating disorder or suicidal attempts, or feelings of suicidal thoughts or behaviours in the last month\*\* * Unstable angina, or myocardial infarction/ cardiovascular surgery / coronary stenting in the last month. * Any serious medical or psychiatric illness likely to interfere with study participation as per the judgment of the investigator (e.g. cirrhosis, active cancer, decompensated schizophrenia).