Colorectal Cancer and Subsequent Diabetes Risk: A Population-based Cohort Study in Taiwan.

Context: The association between colorectal cancer (CRC) and new-onset diabetes mellitus remains unclear.

Objective: To examine the association between CRC and the risk of subsequent diabetes mellitus and to further investigate the impact of chemotherapy on diabetes mellitus risk in CRC.

Design: A nationwide cohort study.

Methods: Using the Taiwan Cancer Registry Database (2007-2018) linked with health databases, 86,268 patients with CRC and an equal propensity score-matched cohort from the general population were enrolled. Among them, 37,277 CRC patients from the Taiwan Cancer Registry (2007-2016) were analyzed for diabetes mellitus risk associated with chemotherapy. Chemotherapy exposure within 3 years of diagnosis was categorized as no chemotherapy, <90 days, 90-180 days, and >180 days. Differences in diabetes mellitus risk were assessed across these categories.

Results: Each group involved 86,268 participants after propensity score matching. The patients with CRC had a 14% higher risk of developing diabetes mellitus than the matched general population (hazard ratio [HR]: 1.14, 95% confidence interval [CI]: 1.09-1.20). The highest risk was observed within the first year after diagnosis followed by a sustained elevated risk. Long-term chemotherapy (>180 days within 3 years) was associated with a 60-70% increased risk of subsequent diabetes mellitus (HR: 1.64, 95% CI: 1.07-2.49).

Conclusion: Patients with CRC are associated with an elevated risk of diabetes mellitus, and long-term chemotherapy, particularly involving capecitabine, increases diabetes mellitus risk. Thus, monitoring blood glucose levels is crucial for patients with CRC, especially during extended chemotherapy.