Objective:Tai chi has been recommended for treating type 2 diabetes mellitus.The purpose of this systematic review was to evaluate evidence from controlled clinical trials testing the effectiveness of tai chi in treating type 2 diabetes mellitus.Methods:Systematic searches were conducted on 14 electronic databases without restrictions on either population characteristics or language of publication.The outcome measures considered for inclusion were changes in fasting blood glucose(FBG),glycosylated haemoglobin A_(1c)(HbA_(1c)) and quality of life(QOL).Results:Eight randomised clinical trials(RCTs) and two controlled clinical trials(CCTs) met all inclusion criteria.Three RCTs from 1 trial compared the effects of tai chi with sham exercise and failed to show effectiveness of tai chi on FBG,HbA_(1c),or QOL.The other 3 RCTs tested the effects of tai chi compared with other types of exercise on FBG.The meta-analysis failed to show an FBG-lowering effect of tai chi[n=118,weighted mean difference(WMD):-0.14 mmol/L,95%CI:-0.86 to 0.58,P=0.70].Four studies (2 RCTs and 2 CCT) compared tai chi with no treatment or self-management programme and failed to report significant differences between the experimental and control groups except for QOL from 1 RCT and 1 CCT. Conclusion:The existing evidence does not suggest that tai chi is an effective therapy for type 2 diabetes. Currently,there are few high-quality trials on which to make definitive judgements. Objective: Tai chi has been recommended for treating type 2 diabetes mellitus. The purpose of this systematic review was to evaluate evidence from controlled clinical trials testing the effectiveness of tai chi in treating type 2 diabetes mellitus. Methods: Systematic searches were conducted on 14 electronic databases without restrictions on either population characteristics or language of publication. The outcome measures considered for inclusion were changes in fasting blood glucose (FBG), glycosylated hemoglobin A_ (1c) (HbA_ (1c)) and quality of life (QOL). Results: Eight randomized clinical trials (RCTs) and two controlled clinical trials (CCTs) met all inclusion criteria. Thre RCTs from 1 trial compared to the effects of tai chi with sham exercise and failed to show effectiveness of tai chi on FBG, HbA_ (1c), or QOL. The other 3 RCTs tested the effects of tai chi compared with other types of exercise on FBG. The meta-analysis failed to show an FBG-lowering effect of tai chi [n = 118, weighted mean differe Studies (2 RCTs and 2 CCT) compared tai chi with no treatment or self-management program and failed to report significant (WMD): -0.14 mmol / L, 95% CI: -0.86 to 0.58, P = 0.70] differences between the experimental and control groups except for QOL from 1 RCT and 1 CCT. Conclusion: The existing evidence does not suggest that tai chi is an effective therapy for type 2 diabetes. Currently, there are few high-quality trials on which to make definitive judgements.