Incidence of cancer in a population-based cohort of patients with type 2 diabetes

Aims Literature suggests that patients with type 2 diabetes may be at increased risk of certain cancers. The objective of this study was to quantify and compare the incidence of melanomas and cancers of the colon/rectum, bladder, liver, and pancreas in patients with and without type 2 diabetes. Materials and methods Using a large national population-based database, we conducted a retrospective cohort study of patients with diabetes (N = 191,223) and a comparison cohort of patients without diabetes (N = 251,489). Using medical record review and claims-based adjudication, we identified newly diagnosed cases of cancer. We calculated and compared cancer incidence rates in patients with and without diabetes. Poisson regression models were fit to obtain crude rate ratios (RR) and 95% confidence intervals (CI); RRs were also adjusted for age, gender, and selected cancer risk factors. Results Overall, we identified 1,165 cancer cases. Patients with diabetes had a greater than three-fold increase in pancreas cancer (RR = 3.31, 95% CI = 2.12-5.15) and a greater than two-fold increase in bladder cancer (RR = 2.35, 95% CI = 1.76-3.15). The rate ratios for colorectal cancer and melanoma were RR = 1.99 (95% CI = 1.64-2.40) and RR = 1.63 (95% CI = 1.21-2.19), respectively. Conclusions These findings support a link between diabetes and pancreas, bladder, colon/rectum and melanoma cancer development. (C) 2008 Diabetes India. Published by Elsevier Ltd. All rights reserved.