A population-based cohort study in Taiwan-use of insulin sensitizers can decrease cancer risk in diabetic patients?

The purpose of the study was to explore the possible association between the use of insulin sensitizers (thiazolidinediones, TZDs) and the risk of cancer in Taiwanese diabetic patients. From the National Health Insurance Research Database (NHIRD) of Taiwan, we identified 22 910 diabetic patients newly diagnosed from 2001 to 2009 and 91 636 non-diabetic comparisons frequency matched with age, sex, and calendar year, excluding those with cancer at the baseline. Among the diabetics, 4159 patients were treated with TZDs and the rest of 18 752 patients were on other anti-diabetic medications (non-TZDs). In comparison to the non-diabetes group, the non-TZDs group had an increased risk of developing cancer [the adjusted hazard ratio (HR): 1.20 and 95% confidence interval (CI) = 1.11-1.30]. The TZDs group had a HR of 1.18 (95% CI = 0.98-1.42). Analysis of site-specific cancer risks showed that both TZDs and non-TZDs groups with elevated risks of colorectal and pancreatic cancer. However, the non-TZDs group had an increased risk of liver cancer when comparing with TZD and non-diabetes groups. This study suggests that patients with diabetes are at an elevated risk of cancer (especially in colorectal and pancreatic cancers), and the use of TZDs might decrease the liver cancer risk in diabetic patients. Further investigation using large samples and rigorous methodology is warranted.