• Diabetes Mellitus;
  • Colorectal Cancer;
  • Meta-Analysis


Aim:  The incidence and mortality of colorectal cancer (CRC) were quantified in persons with and without diabetes mellitus (DM).

Method:  MEDLINE and EMBASE were searched for articles published before July 2010. Cohort studies that evaluated DM and CRC incidence and mortality were included. The initial search identified 1887 titles, of which 24 articles met the inclusion criteria. We defined the relative risk (RR) as the metric of choice, with 95% confidence intervals (CIs) were calculated with a random-effects model.

Results:  There was an increase in the RR of developing colorectal cancer in persons with diabetes compared with those without diabetes (RR 1.28 [95%CI 1.19 - 1.39]), without heterogeneity between studies (Pheterogeneity = .13). The association between duration of DM and CRC incidence was stronger in 11–15 yr group (RR 1.51 [95%CI 1.12 - 2.03]) than in < 10 yr (RR 1.05 [95%CI 0.90 - 1.22]) and >15 yr group (RR 1.25 [95%CI 0.80 - 1.94]), and there was significant heterogeneity among subgroups (Pheterogeneity = .01). In studies reporting standardized incidence ratios (SIR), there was an increased incidence of CRC with DM (RR 1.27 [95%CI 1.14 - 1.42] Pheterogeneity = .09); and the association was stronger among males (RR 1.47 [95%CI 1.15 - 1.86]) than females (RR 1.08 [95%CI 1.00 - 1.17]), there was significant heterogeneity among gender (Pheterogeneity = .01).

Conclusion:  This meta-analysis suggests diabetic individuals have a significant increase in risk of developing colorectal cancer.