Association of type 2 diabetes and colon adenomas

Type 2 diabetes mellitus (DM) is associated with hyperinsulinemia, which may lead to increased risk of carcinogenesis by increasing insulin-like growth factor-1 level. In this study, we sought to determine the association between type 2 DM and colon adenomas.

In this retrospective case-control study, all the colonoscopies performed in an urban medical center during a 3-year period were reviewed. Patients with adenomatous polyps were considered as cases (n = 261). Age- and sex-matched controls with a 2:1 ratio were selected (n = 522). Among diabetic subjects, the association of different anti-diabetic medications and HbA1C level with high-risk adenoma features was analyzed.

Type 2 DM was significantly associated with colon adenomas (odds ratio (OR) = 1.45, 95% confidence interval (CI) = 1.05-2.01, p = 0.024). Exposure to insulin (OR = 1.734, 95% CI = 1.13-2.65, p = 0.013) and thiazolidinediones (OR = 2.83, 95% CI = 1.28-6.26, p = 0.01) was associated with developing adenomas. Neither the type of antidiabetic medication nor the level of HbA1C was a predictor for high-risk adenomas. Smoking (OR = 1.47, 95% CI = 1.07-2.02, p = 0.02), use of aspirin (OR = 1.59, 95% CI = 1.15-2.20, p = 0.005), and statins (OR = 1.54, 95% CI = 1.13-2.10, p = 0.007) appeared to increase the risk of adenomas.

This study shows a significant association between type 2 DM and colon adenomas. Establishing this association may lead to inclusion of diabetic patients in the high-risk group for developing colorectal cancer.