Glucagon-like peptide-1 receptor agonist treatment reduces body weight and improves glycaemic outcomes in patients with concurrent overweight/obesity and type 1 diabetes: A systematic review and meta-analysis

Aims: This systematic review and meta-analysis evaluated the long-term efficacy and safety of glucagon-like peptide-1 receptor agonists (GLP-1RAs) as adjunctive therapies for individuals with type 1 diabetes (T1D) and overweight or obesity. Materials and Methods: A literature search was conducted in June 2023 and updated in June 2025. Eligible studies included adults with T1D, body mass index ≥25 kg/m², and GLP-1RA treatment alongside insulin for ≥12 weeks. Changes in body weight, HbA1c, and insulin dose were expressed as mean differences (MDs) with 95% confidence intervals (CIs). Safety outcomes were assessed using odds ratios (ORs) with 95% CIs. Data were pooled using random-effects models. Results: Exactly 13 studies met the inclusion criteria. GLP-1RA treatment was associated with a body weight reduction of 4.31 kg (95% CI: 3.61–5.00 kg) and a HbA1c reduction of 0.25% (95% CI: 0.18–0.32%). Across all studies, insulin dosage was reduced by 9.24 U/day (95% CI: 7.04–11.45 U/day). Subgroup analysis identified that semaglutide achieved the greatest reductions in all outcome measures. Hypoglycaemic episodes were increased (OR = 1.34; 95% CI: 1.02–1.76), while hyperglycaemic episodes decreased (OR: 0.69, 95% CI: 0.56–0.87). Gastrointestinal adverse events, including nausea and vomiting, were significantly more frequent with GLP-1RA treatment, though no increase in serious adverse events was observed. Conclusions: GLP-1RAs are effective for body weight reduction and glycaemic improvement in individuals with T1D and overweight/obesity, with acceptable safety profiles. These findings provide evidence that GLP-1RAs can be effectively and safely used as adjunctive therapy to insulin in people with T1D, but additional robust randomised clinical trials are needed.