ObjectiveTo systematically evaluate the safety of dipeptidyl peptidase-4 (DPP-4) inhibitors on the risk of cardiovascular events in type 2 diabetes mellitus (T2DM) patients. MethodsDatabases such as the Cochrane Library, PubMed, Elsevier ScienceDirect and EMbase were searched to collect randomized controlled trials (RCTs) about DPP-4 inhibitors for T2DM patients from inception to February 2014. Two reviewers independently screened literature according to the inclusion and exclusion criteria, extracted data and assessed the methodological quality of included studies. Then, meta-analysis was performed using RevMan5.2 software. ResultsA total of 20 RCTs involving 10 402 patients were included. The results of meta-analysis showed that:there were no significant differences between the DPP-4 inhibitors group and the control group in the cardiovascular adverse events (RR=0.86, 95%CI 0.62 to 1.20, P=0.38) and acute coronary syndrome (RR=0.66, 95%CI 0.37 to 1.17, P=0.15). Subgroup analyses by type of liptins and durations showed there were lower risks of adverse cardiovascular events in the DPP-4 inhibitors group of the sitagliptin subgroup (RR=0.49, 95%CI 0.29 to 0.82, P=0.007) and the duration of ≥52 weeks subgroup (RR=0.62, 95%CI 0.39 to 0.97, P=0.04). No significant difference was found between the two groups in hypertension events (RR=1.09, 95%CI 0.84 to 1.40, P=0.52). ConclusionThe DPP-4 inhibitors are relatively safe. In the long-term treatment of T2DM, the sitagliptin could not only effectively control the level of blood sugar but also might obtain benefits in cardiovascular aspects.