In a real‑world study of people with type 1 diabetes and obesity, tirzepatide caused the biggest weight drop (about 11% of body weight) over a year, with modest improvements in blood sugar and no severe low‑blood‑sugar or ketoacidosis events. Semaglutide and liraglutide also helped weight loss but a bit less. These drugs could be useful as add‑on treatments for weight control in T1D, but they’re not officially approved for this use yet.

This study aimed to compare the effects of tirzepatide, semaglutide, and liraglutide on body weight and metabolic risk markers over 12 months in people with body mass index ≥27 kg/m² and type 1 diabetes (T1D). This real-world study included 250 people with obesity and T1D (female = 54.8%), treated with either tirzepatide (n = 35), semaglutide (n = 36), liraglutide (n = 97) or usual care (n = 82). Secondary outcomes included changes in lipid profile, renal and liver markers, blood pressure, and HbA1c. All three agents led to significant weight loss. Tirzepatide showed the greatest reduction of weight loss (10.9%; p < 0.001), followed by semaglutide (9.9%; p < 0.001) and liraglutide (7.1%; p < 0.001). Dose-dependent reductions were observed for tirzepatide and semaglutide. Tirzepatide, semaglutide and liraglutide modestly reduced HbA1c by 0.65% (p = 0.004), 0.33% (p = 0.034) and 0.23% (p = 0.017), respectively. LDL-cholesterol was reduced by semaglutide (p = 0.05) and liraglutide (p = 0.02), and liraglutide also lowered the urine albumin-to-creatinine ratio (p = 0.007). There was no change in body weight and HbA1c in the usual care group. No severe hypoglycaemia or diabetic ketoacidosis (DKA) events were reported in any group. Tirzepatide, semaglutide, and liraglutide reduced bodyweight and improved in selected metabolic risk markers over 12 months without increasing the risk for hypoglycaemia or DKA. Weight loss appeared less compared with patients without diabetes. Tirzepatide, semaglutide and liraglutide modestly improved glycaemic control in adults with T1D and obesity. These findings support the potential adjunctive role of GLP-1 receptor agonists in people with obesity and T1D and underscore the need for further validation through randomized controlled trials.