Objective To assess the efficacy and safety of berberine(BBR) in patients with type 2 diabetes mellitus(T2DM) by performing a systematic review. Methods PubM ed, Cochrane Library, Embase, CNKI, and CBM were searched until May 2014. The randomized controlled trials(RCTs) of the effects of BBR on blood glucose in patients with T2 DM were included. The quality of RCTs was assessed by the Jadad scale, and the Review Manager 5.1 software was used for data syntheses and analyses. Results Seventeen RCTs involving 1198 patients were included. The methodological quality of these RCTs was generally low. Compared with the control groups(placebo or no intervention with medicine), BBR suggested the statistically significant benefits in improving fasting blood glucose(FBG), postprandial blood glucose(PBG), glycosylated hemoglobin, and homeostasis model assessment of insulin resistance. Subgroups analysis of BBR compared with metformin(MET) showed that 1.5g/d MET was significantly better than BBR(0.9-1.5 g/d) in lowering FBG and PBG. However, there was no significant difference between 1.5g/d BBR and 0.75g/d MET groups in blood glucose profiles. In comparison with rosiglitazone, BBR suggested the statistically significant benefits in lowering FBG. And there was no significant difference between BBR and glipizide groups in blood glucose profiles. In addition, the combination therapy of BBR and oral hypoglycemic agents had the advantages over oral hypoglycemic agents alone. No serious adverse effects of BBR have been reported. Conclusion BBR may have the beneficial effects in the control of blood glucose levels, though the efficacy of BBR is not superior to MET. BBR appeares to have advantages over rosiglitazone in improving FBG levels. In addition, the combination therapy of BBR and oral hypoglycemic agents may be a new attempt. However, the efficacy of BBR in patients with T2 DM should be further evaluated by more RCTs in a larger population of patients. Objective To assess the efficacy and safety of berberine (BBR) in patients with type 2 diabetes mellitus (T2DM) by for a systematic review. Methods PubM ed, Cochrane Library, Embase, CNKI, and CBM were searched until May 2014. The randomized controlled trials (RCTs) of the effects of BBR on blood glucose in patients with T2 DM were included. The quality of RCTs was assessed by the Jadad scale, and the Review Manager 5.1 software was used for data syntheses and analyzes. Results Seventeen RCTs involving 1198 Compared with the control groups (placebo or no intervention with medicine), BBR suggested the significant effects in improving fasting blood glucose (FBG), postprandial blood glucose (PBG), Subgroups analysis of BBR compared with metformin (MET) showed that 1.5g / d MET was significantly better than BBR (0.9 However, there was no significant difference between 1.5g / d BBR and 0.75g / d MET groups in blood glucose profiles. In a comparison with rosiglitazone, BBR suggests the significant significant in lowering -1.5 g / d And there was no significant difference between BBR and glipizide groups in blood glucose profiles. In addition, the combination therapy of BBR and oral hypoglycemic agents had the advantages over oral hypoglycemic agents alone. No serious adverse effects of BBR have been reported. Conclusion BBR may have the beneficial effects in the control of blood glucose levels, though the efficacy of BBR is not superior to MET. BBR appeares to have advantages over rosiglitazone in improving FBG levels. In addition, the combination therapy of BBR and oral hypoglycemic agents may However, the efficacy of BBR in patients with T2 DM should be further evaluated by more RCTs in a larger population of patients.