Duration of diabetes mellitus and risk of kidney and bladder cancer: a longitudinal nationwide cohort study.

Previous studies have suggested that diabetes mellitus (DM) may increase the risk of kidney and bladder cancer; however, little is known about the duration of DM. We aimed to analyze the risk of kidney and bladder cancer according to the duration of DM in a longitudinal nationwide cohort. This study was conducted in a cohort of 9,773,462 participants ≥ 20 years old who underwent a National Health Examination in 2009 and were followed up until December 2017. Cox-proportional hazard models were used to evaluate the risk of kidney and bladder cancer in relation to the duration of DM. During follow-up (mean 7.3 years), kidney and bladder cancer occurred in 11,219 and 13,769 participants, respectively. DM was associated with an increased risk of kidney and bladder cancer (hazard ratio (HR), 95% confidence interval (95% CI); 1.14, 1.09-1.20 and 1.23, 1.17-1.28, respectively). Compared to fasting glucose < 100 mg/dL, impaired fasting glucose (IFG) and longer DM duration were associated with increased risks (HR, 95% CI): IFG (1.05, 1.01-1.10), new-onset DM (1.13, 1.03-1.24), DM < 5 years (1.11, 1.02-1.20), and DM ≥ 5 years (1.25, 1.15-1.36) in kidney cancer; IFG (1.05, 1.01-1.09), new-onset DM (1.10, 1.01-1.19), DM < 5 years (1.26, 1.18-1.35), and DM ≥ 5 years (1.34, 1.26-1.43) in bladder cancer, respectively. Our findings suggest that the subjects with IFG and longer duration of DM had a higher risk for kidney and bladder cancer than those without DM.