Researchers identified an association between type 2 diabetes and colorectal cancer (CRC) among men. The association did not hold for women. The new study, published in the October issue of Gastroenterology, found that the risk existed regardless of insulin use. Insulin use, in fact, was found to be associated with a slight but not substantially increased risk of CRC.
Using the Cancer Prevention Study II Nutrition Cohort, Campbell and colleagues identified 1567 of 73,312 men and 1242 of 81,663 women diagnosed with CRC by from 1992 to 2007. Of these, 227 men and 108 women had type 2 diabetes. Among men, type 2 diabetes increased the risk of incident CRC compared with not having the disease (relative risk [RR], 1.24; 95% confidence interval [CI], 1.08-1.44). Men using insulin for type 2 diabetes further increased risk, for a RR of 1.36 (95% CI, 1.05-1.78). For those not using insulin, RR was 1.22 (95% CI, 1.04-1.45). Among women, type 2 diabetes did not increase risk (RR, 1.01; 95% CI, 0.82-1.23). Using insulin for the disease also did not increase risk among women (RR, 0.95; 95% CI, 0.64-1.41).