Objective: To investigate the effects of Tai chi in type 2 diabetes mellitus (type-2 DM) patients using systematic review and meta-analysis. Methods: Seven electronic resource databases were searched, and randomized controlled trials on the role of Tai chi in type-2 DM patients were retrieved. The meta-analysis was performed with RevMan 5.3, and research quality evaluation was conducted with the modified Jadad scale. Results: Fourteen studies, with 798 individuals related to the intervention of Tai chi on diabetes, were included. The results showed that, compared with nonexercise, Tai chi had the effect of lowering fasting blood glucose [MD = -1.39, 95% CI (-1.95, -0.84), P < 0.0001] and the subgroup effect size decreased with the increase of total exercise amount, there is no significant difference between Tai chi and other aerobic exercises [MD = -0.50, 95% CI (-1.02, 0.02), P = 0.06]; compared with nonexercise, Tai chi could reduce HbA1c [MD = -0.21, 95% CI (-0.61, 0.19), P = 0.31], and the group effect size decreased with the increase of total exercise amount. The reducing HbA1c effect of Tai chi was better than that of other aerobic exercises, but the difference was at the margin of statistical significance [MD = -0.19, 95% CI (-0.37, 0.00), P = 0.05]; compared with nonexercise, Tai chi had the effect of reducing 2 h postprandial blood glucose [MD = -2.07, 95% CI (-2.89, -1.26), P = 0.0002], there is no significant difference between Tai chi and other aerobic exercises in reducing 2 h postprandial blood glucose [MD = -0.44, 95% CI (-1.42, 0.54), P = 0.38]. Conclusion: Tai chi can effectively affect the management of blood glucose and HbA1c in type-2 DM patients. Long-term adherence to Tai chi has a better role in reducing blood glucose and HbA1c levels in type 2 DM patients.