Cancer risk among patients with type 2 diabetes mellitus: a population-based prospective study in China.

Evidence indicates an increased cancer risk among type 2 diabetes mellitus (T2DM) patients, yet studies in mainland China are scarce. Based on Diabetes Surveillance System linking to Cancer Surveillance System of Zhejiang Province in China, we explored the cancer risk among T2DM patients. Totally, 327,268 T2DM patients were identified and followed from January 1, 2007 to December 31, 2013. Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) were reported. Overall cancer risk was found significantly increased with an SIR of 1.15 (95% CI 1.12-1.19) and 1.25 (95% CI 1.21-1.30) in males and females, respectively. Regarding specific cancer sites, risks of liver, colon, rectum, pancreas, and kidney were significantly increased with SIRs of 1.26 (95% CI 1.16-1.36), 1.47 (95% CI 1.29-1.67), 1.25 (95% CI 1.09-1.43), 2.81 (95% CI 2.50-3.16) and 1.61 (95% CI 1.28-2.03) in males, 1.53 (95% CI 1.35-1.73), 1.33 (95% CI 1.15-1.54), 1.29 (95% CI 1.10-1.51), 3.62 (95% CI 3.20-4.09) and 1.71 (95% CI 1.28-2.29) in females, respectively. A significant increased SIR was noted for prostate (1.80, 95% CI 1.58-2.06). Significant increased SIRs for lung (1.32, 95% CI 1.20-1.44) and stomach (1.16, 95% CI 1.03-1.30) were observed in females. We suggested an increased cancer risk among T2DM patients.