Insulin levels are associated with risk of colon adenoma and not nonadenomatous polyps: A retrospective, hospital-based study.

Recently, the prevalence of colorectal cancer has been increasing in Korea. Several studies have reported that adenomatous polyps, known as precancerous lesions, are associated with increased blood insulin levels. The principal objective of the present study was to examine the correlation between insulin levels and colon polyps in subjects without a history of diabetes or colorectal cancer. From January 2, 2018 to December 31, 2019, 3277 adults who visited the University Hospital Health Examination Center and underwent colonoscopy were included in this study. Insulin, glycated hemoglobin (HbA1c), and fasting blood glucose levels were measured, and past medical history, alcohol consumption, smoking, and physical activity were assessed using self-administered questionnaires. Among the 3277 subjects, the prevalence of adenomatous and nonadenomatous lesions were 22.2% and 11.5%, respectively. The mean values of insulin, HbA1c, and fasting blood glucose were significantly increased in the adenomatous and nonadenomatous polyp groups compared to the normal group. Logistic regression analysis showed that the risk of adenoma (odds ratio [OR] 1.483; 95% confidence interval [CI], 1.170-1.878) and nonadenomatous polyps (OR 1.415; 95% CI, 1.038-1.929) were increased in the high insulin level group (≥7.36 uIU/mL), and only the risk of adenoma (OR 1.312; 95% CI, 1.003-1.718) was significantly higher after adjustment for disturbance variables. This study suggests that an increase in insulin levels is a significant risk factor for colon adenoma.