Type 2 Diabetes and Risk of Early-Onset Colorectal Cancer

Abstract

ABSTRACTObjectiveEarly-onset colorectal cancer (CRC) is increasing in many developed countries. Type 2 diabetes mellitus has increased substantially in younger adults; however, its role in early-onset CRC remains unidentified.DesignWe conducted a claims-based nested case-control study using IBM® MarketScan® Commercial Database (2006-2015). Incident early-onset CRC diagnosed at ages 18-49 were identified by ICD-9-CM diagnosis code, and the first coded diagnostic pathology date was assigned as the index date. Controls were frequency matched with cases. Type 2 diabetes, stratified by severity, was identified through ICD-9-CM using the Klabunde algorithm. Multivariate logistic regressions were used to estimate odds ratios (ORs) and 95% confidence intervals (Cls).ResultsA total of 6001 early-onset CRC and 52104 controls were included. Type 2 diabetes was associated with an increased risk of early-onset CRC (5.0% in cases vs. 3.7% in controls; OR 1.24; 95% CI 1.09 to 1.41). The positive association was more pronounced for uncontrolled (OR 1.37; 95% CI 1.12 to 1.67) or complicated (OR 1.59; 95% CI 1.08-2.35) type 2 diabetes compared to controlled diabetes (OR 1.13; 95% CI 0.94 to 1.36). The positive association was driven by proximal (OR 1.35; 95% CI 1.03 to 1.77) and distal (OR 1.67; 95% CI 1.30 to 2.15) colon cancer but not rectal cancer.ConclusionsIndividuals with type 2 diabetes have a higher risk of early-onset CRC, with stronger associations for uncontrolled/complicated diabetes. The rising prevalence of type 2 diabetes among younger adults in the US may partially contribute to the increasing incidence of early-onset CRC.