Incidence of bladder cancer in type 2 diabetes mellitus patients

Background and objectives: Type 2 diabetes mellitus (T2DM) is becoming increasingly prevalent worldwide and is associated with increased incidence of kidney cancer and bladder cancer (BC). However, studies have produced conflicting results. Therefore, we retrospectively evaluated the incidence of BC in T2DM patients using the Taiwan National Health Insurance Research Database (NHIRD). Materials and Methods: We included 31,932 patients with a diagnosis of T2DM in the study group and 63,864 age-and sex-matched patients without T2DM at a ratio of 1:2 in the control group. The primary outcome was the diagnosis of BC. Cox proportional hazards regression was used to evaluate the incidence and adjusted hazard ratio (aHR) of BC in the multivariate model. Results: After a 16-year follow-up, we found that 67 BC cases occurred in the study group and 152 BC events in the non-T2DM group without a significantly higher risk (aHR: 0.842, 95% confidence interval: 0.627–1.13). Conclusions: T2DM patients do not have a higher risk of BC.