Comorbid diabetes mellitus and risk of death after diagnosis of colorectal cancer: A population-based study

Background: The few studies that have examined the association between comorbid diabetes mellitus (DM) and survival after diagnosis of colorectal cancer have involved small numbers of patients with DM, and cause of death was not examined. Methods: All 542 African American (black) and 8853 white Connecticut residents diagnosed with colorectal cancer in 1994–1999 were identified from the population-based statewide Connecticut cancer registry. Comorbid DM was defined as an inpatient hospital admission (prior to or around the time of colorectal cancer diagnosis) that included DM as one of up to 10 discharge diagnoses. Results: Comorbid DM, identified for 1014 (10.8%) of the 9395 patients, was associated with a statistically significantly elevated risk of death from any cause (hazard ratio or HR = 1.38, 95% confidence interval 1.27–1.49), in a proportional hazards regression model that included age, sex, race and extent of disease at diagnosis. This finding was due to an elevated risk of death from causes of death other than colorectal cancer. Conclusions: Studies are needed on quality of care for comorbid DM and its complications among colorectal cancer patients.