Risk of Diabetes in Subjects with Positive Fecal Immunochemical Test: A Nationwide Population-Based Study

BACKGROUND: Positive fecal immunochemical test (FIT) results have been recently suggested as a risk factor for systemic inflammation. Diabetes induces inflammation in the gastrointestinal tract via several ways. We investigated the association between FIT results and the incidence of diabetes. METHODS: A total of 7,946,393 individuals aged ≥50 years from the National Cancer Screening Program database who underwent FIT for colorectal cancer (CRC) screening from 2009 to 2012 were enrolled. The primary outcome was newly diagnosed diabetes based on the International Classification of Disease 10th revision codes and administration of anti-diabetic medication during the follow-up period. RESULTS: During a mean follow-up of 6.5 years, the incidence rates of diabetes were 11.97, 13.60, 14.53, and 16.82 per 1,000 personyears in the FIT negative, one-positive, two-positive, and three-positive groups, respectively. The hazard ratios (HRs) for the incidence of diabetes were 1.14 (95% confidence interval [CI], 1.12 to 1.16; HR, 1.21; 95% CI, 1.16 to 1.27; and HR, 1.40; 95% CI, 1.28 to 1.55) in the one-positive, two-positive, and three-positive FIT groups compared with the FIT negative group, respectively. The effect was consistent in individuals with normal fasting blood glucose (adjusted HR 1.55 vs. 1.14, P for interaction <0.001). CONCLUSION: Positive FIT results were associated with a significantly higher risk of diabetes, suggesting that the FIT can play a role not only as a CRC screening tool, but also as a surrogate marker of systemic inflammation; thus, increasing the diabetes risk.