Colorectal Cancer Risks According to Sex Differences in Patients With Type II Diabetes Mellitus: A Korean Nationwide Population-Based Cohort Study

INTRODUCTION: Developing colorectal cancer (CRC) poses challenges for patients with type II diabetes mellitus (T2DM). We investigated CRC risk factors in patients with T2DM. METHODS: We retrospectively collected data from the National Health Insurance Corporation database, comprising approximately 97% of the Korean population. T2DM and CRC were defined according to International Classification of Disease codes (10th Revision) and claims data. Obesity was defined using body mass index (BMI); abdominal obesity was defined according to waist circumference. Other variables were defined using demographic, anthropometric, and laboratory data. RESULTS: Overall, 2,591,149 patients with T2DM were analyzed. During the follow-up period (median, 5.4 years), 24,236 CRC cases were identified. Aging (≥70 years), male sex, smoking, alcohol consumption, hypertension, and insulin and/or sulfonylurea use were significant risk factors for CRC. In males, smoking and alcohol consumption were more likely to lead to CRC, whereas a BMI increase was a more significant risk factor in females. Females with a BMI ≥ 25 kg/m(2) and abdominal obesity were associated with an 18% increased risk of CRC compared with patients with normal weight and normal waist circumference (hazard ratio = 1.184, 95% confidence interval 1.123–1.25), whereas male patients with a BMI ≥ 25 kg/m(2) and abdominal obesity were associated with an 8% increased risk (hazard ratio = 1.087, 95% confidence interval 1.049–1.127). DISCUSSION: Patients had CRC risk factors that differed according to sex. Smoking and heavy alcohol consumption were risks of CRC in males. Female patients with a BMI ≥ 25 kg/m(2) and abdominal obesity were at a higher risk of developing CRC than males.