Objective: To systematically synthesize and critically evaluate evidence on the effects of tai chi for pa-tients with type 2 diabetes mellitus.Data sources: Seven electronic databases (Wan Fang, SinoMed, China National Knowledge In-frastructure, VIP, PubMed, Embase, and Cochrane Library) were systematically searched from their in-ception to March 2018.Study selection: Randomized controlled trials in-vestigating the effects of tai chi on individuals with type 2 diabetes mellitus were eligible.Data extraction: Biomedical outcomes (fasting plas-ma glucose, glycosylated haemoglobin (HbA1c), fasting insulin, insulin resistance, body mass index, total cholesterol, blood pressure) as well as balance and quality of life-related outcomes were extracted independently by 2 reviewers. Stata 12.0 software was used to synthesize data if there was no or mo-derate heterogeneity across studies. Otherwise, nar-rative summaries were performed.Data synthesis: A total of 23 studies (25 articles) involving 1,235 patients were included in this me-ta-analysis. Signicant changes in tai chi-related effects were observed in lowering fasting plasma glucose (standardized mean difference; SMD –0.67; 95% condence interval (95% CI) –0.87 to –0.47; p < 0.001), HbA1c (mean difference; MD–0.88%; 95% CI –1.45% to –0.31%; p =0.002) and insu-lin resistance (MD –0.41; 95% CI –0.78 to –0.04; p = 0.029). Benecial effects of tai chi were also found in decreasing body mass index (MD –0.82 kg/m2; 95% CI –1.28 to –0.37 kg/m2; p < 0.001) and to-tal cholesterol (SMD –0.59; 95% CI –0.90 to –0.27; p < 0.001). In addition, tai chi reduced blood pressu-re (systolic blood pressure (MD –10.03 mmHg; 95% CI –15.78 to –4.29 mmHg; p = 0.001), diastolic blood pressure (MD –4.85 mmHg; 95% CI –8.23 to –1.47 mmHg; p = 0.005)) and improved quality of life-rela-ted outcomes (physical function (MD 7.07; 95% CI 0.79–13.35; p = 0.027), bodily pain (MD 4.30; 95% CI 0.83–7.77; p = 0.015) and social function (MD 13.84; 95% CI 6.22–21.47; p < 0.001)). However, no impact was exerted on fasting insulin (SMD –0.32; 95% CI –0.71 to 0.07; p = 0.110) or balance (MD 2.71 s; 95% CI –3.29 to 8.71 s; p = 0.376).Conclusion: Tai chi is effective in controlling biome-dical outcomes and improving quality of life-related outcomes in individuals with type 2 diabetes melli-tus, although no effects were observed on balance and fasting insulin. Further high-quality research is needed to elucidate the effects of different types of tai chi, the long-term effects of tai chi, the impact on respiratory function, and the association between tai chi and the risk of developing type 2 diabetes mel-litus in healthy individuals