GLP-1 receptor agonist use and overall survival among women with type 2 diabetes and breast cancer: a retrospective cohort study

Background Diabetes and obesity are associated with worse prognosis in women with breast cancer. However, the impact of glucagon-like peptide-1 receptor agonists (GLP-1RA) on survival following breast cancer diagnosis remains unclear. Methods We conducted a single institution, propensity-score matched, retrospective, 2-year landmark study of women with type 2 diabetes (T2D) diagnosed with breast cancer at City of Hope (2009-2025). Patients were categorized based on post-diagnosis exposure to GLP-1RA. Patients were compared across exposure groups using t-tests for continuous variables, chi-square tests for categorical variables, multivariable Cox proportional hazards models for overall mortality risk, and Kaplan-Meier plots for survival time. Results In 226 matched pairs, there were 47 deaths (30 in unexposed patients and 17 in exposed patients). GLP-1RA exposure was associated with a significantly lower risk of overall mortality (HR = 0.51, 95% CI 0.28-0.93, p = 0.03) on multivariable analysis. A sensitivity analysis in stage I-III patients yielded similar results (HR = 0.45, 95% CI 0.23-0.85, p = 0.03). Kaplan-Meier survival analysis also showed an association between increased overall survival and GLP-1RA exposure (log-rank p = 0.02). Conclusions In this retrospective cohort of women with T2D and breast cancer, GLP-1RA use after diagnosis was associated with improved overall survival in T2D. These findings reflect all-cause mortality and do not distinguish between cancer-specific and non-cancer causes of death and should therefore be interpreted accordingly.