Antidiabetic medications and the risk of colorectal cancer in patients with diabetes mellitus: a meta-analysis of observational studies

Abstract

Objective To evaluate prescription of metformin, insulin and sulfonylureas and the risk of colorectal cancer. Methods We conducted a systematic search of multiple bibliographic databases, such as PubMed, Embase, Cochrane Library, ISI Web of science, from December 2010 to December 2015, for articles that evaluated exposure to metformin and insulin, SU and the study of the relationship between the risk of T2DM in patients with colorectal cancer.The main outcome indicator is incidence and the main effect size is the odds ratio (OR) estimated with 95% confidence intervals (CI) using Stata 12.0 statistical software. Results Twelve studies reporting 1 967 404 cases of colorectal cancer in patients with 2 diabetes mellitus were included. Analysis of 3 case-control studies showed that compared with other antidiabetic drugs, metformin treatment reduces 16% (n=2, OR=0.84, 95%CI: 0.77-0.93), the ratio of colorectal cancer in patients with T2DM, insulin treatment was associated with an increase of 44% in the risk of colorectal cancer (n=2, OR=1.44, 95%CI: 1.27-1.64), SU treatment increases the ratio by 18% (n=2, OR=1.18, 95%CI: 1.09-1.28). Analysis of 9 Cohort studies showed that a 28% reduction in colorectal cancer risk associated with metformin use (n=5, OR=0.62, 95%CI: 0.53-0.73), insulin increased the ratio of colorectal cancer by 27% (n=5, OR=1.27, 95%CI: 1.04-1.54), SU treatment increases the colorectal cancer ratio by 29% (n=4, OR=1.29, 95%CI: 1.04-1.59). Conclusion Metformin treatment appears to be associated with a significantly lower risk of colorectal cancer in patients with type 2 diabetes; a trend toward higher colorectal cancer risk was observed with the use of sulfonylurea and insulin. Key words: Colorectal neoplasms; Hypoglycemic agents; Diabetes mellitus; Meta-analysis