This retrospective cohort study aimed to compare the effectiveness of glucagon-like peptide-1 receptor agonists (GLP-1RAs) versus metformin for preventing type 2 diabetes mellitus (T2DM), reducing mortality, and improving body mass index (BMI) in antipsychotic-treated patients with overweight /obesity. We used data from the TriNetX Global Collaborative Network. Adults (aged ≥18 years) with overweight or obesity, antipsychotic exposure, and no prior T2DM diagnosis were identified. After propensity score matching, patients initiating GLP-1RA therapy were compared with those initiating metformin. The primary outcome was incident T2DM occurring between 1 and 5 years after treatment initiation. Secondary outcomes included all-cause mortality and BMI change. Among 9939 eligible patients, 3115 matched pairs were included. The incidence of T2DM was significantly lower in the GLP-1RA group compared with the metformin group (1.96% vs 7.26%; hazard ratio [HR]=0.34; 95% CI, 0.26-0.46; p < 0.001). All-cause mortality was also reduced in the GLP-1RA group (0.32% vs 1.96%; HR, 0.25; 95% CI, 0.13-0.49; p < 0.001). Regarding BMI change, patients receiving GLP-1RA experienced greater weight reduction than those receiving metformin. The mean (standard deviation) change in BMI was -2.66 (8.51) kg/m² in the GLP-1 group versus -1.36 (8.63) kg/m² in the metformin group (p < 0.001). In conclusion, in this large real-world cohort of antipsychotic-treated patients with overweight or obesity, GLP-1RA therapy was associated with significantly lower risks of T2DM and mortality, and greater BMI reduction compared with metformin. These findings suggest that GLP-1RAs may offer a more favorable profile against antipsychotic-induced glucose dysregulation.
