ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the association of diabetes mellitus(DM) with colorectal cancer.</p><p><b>METHODS</b>Case-control study was performed to compare 486 patients with colorectal cancer (study group) and 533 patients without colorectal cancer (control group) in the Affiliated Nanhai Hospital of Southern Medical University between 2006 and 2009.</p><p><b>RESULTS</b>The incidence of DM was 12.1% in study group and 7.1% in the control group, and the difference was significant(P<0.01). On multivariate analysis, DM was independently associated with colorectal cancer (OR=1.886,95% CI:1.450~3.571). Colorectal cancer risk was increased in DM patients with a duration of 5-20 years(P<0.05), while colorectal cancer risk in those with a duration less than 5 years or more than 20 years did not change(P>0.05). No significant differences in tumor differentiation, invasion depth, lymph node involvement, distant metastasis and lymphovascular invasion were found between colorectal cancer patients with and without DM(all P>0.05).</p><p><b>CONCLUSION</b>Diabetes mellitus increases the risk of colorectal cancer, however, biological behaviors of colorectal cancer is not associated with diabetes mellitus.</p>