Association of type 2 diabetes mellitus and the risk of colorectal cancer: A meta-analysis and systematic review

AIM: To provide a quantitative assessment of the association between type 2 diabetes mellitus (T2DM) and the risk of colorectal cancer (CRC). METHODS: Systematic review was conducted thorough MEDLINE, EMBASE, Cochrane Library, and ISI Web of knowledge databases till 31st January 2014. This meta-analysis included the cohort studies that illustrated relative risk (RR) or odds ratio estimates with 95%CI for the predictive risk of CRC by T2DM. Summary relative risks with 95%CI were analyzed by using an effects summary ratio model. Heterogeneity among studies was assessed by the Cochran's Q and I-2 statistics. RESULTS: The meta analysis of 8 finally selected studies showed a positive correlation of T2DM with the risk of CRC as depicted by effects summary RR of 1.21 (95%CI: 1.02-1.42). Diabetic women showed greater risk of developing CRC as their effect summary RR of 1.22 (95%CI: 1.01-49) with significant overall Z test at 5% level of significance was higher than the effect summary RR of 1.17 (95%CI: 1.00-1.37) of men showing insignificant Z test. The effect summary RR of 1.19 with 95%CI of 1.07-1.33 indicate a positive relationship between DM and increased risk of CRC with significant heterogeneity (I-2 = 92% and P-value < 0.05). CONCLUSION: Results from this systematic review and meta-analysis report that diabetic people have an increased risk of CRC as compared to non-diabetics.