Traditional Chinese medicine (TCM) has recorded knowledge of diabetes for over 2000 years. Because a considerable number of TCM studies exhibit design defects, such as limited intervention duration, small sample sizes and inconsistent efficacy evaluations, the role of TCM in the treatment of diabetes cannot be fully elucidated. In this review, we evaluate randomized controlled trials of prediabetes, diabetes and diabetic complications published in the past decade. We found that TCM could significantly improve glucose control and clinical indices in patients with diabetes and effectively delay the progression of diabetes. We also summarize potential pharmacological mechanisms underlying the efficacy of TCM medication/herbs and their active ingredients for treating diabetes. More rigorously designed experiments and long-term evaluation of TCM for diabetes will allow for more effective diabetes management. K E Y W O R D S diabetes, diabetic complications, pharmacological mechanisms, prediabetes, randomized controlled trials, traditional Chinese medicine 1 | INTRODUCTION The overall population of patients with diabetes has reached approximately 415 million and is estimated to rise further to nearly 642 million by 2040. 1 Vast amounts of medical resources are spent on diabetes, and the total global health expenditure because of diabetes was estimated to be $673 billion in 2015; however, a decrease in the incidence of diabetes has not been observed. 1,2 About 5 million deaths are attributed to diabetes each year, and patients with an extended duration of complications lose their ability to work, thereby causing heavy social and economic burdens. Therefore, it is urgent to develop effective strategies to prevent the global health threat of diabetes. Traditional Chinese medicine (TCM) has focused on the treatment of diabetes for thousands of years. The "whole view" and "multi-targets" approaches of TCM provide unique advantages in controlling complex diseases such as diabetes. 3 TCM focuses on individualized treatments that are based on the differentiation of syndromes, control of balance and various routes of administration. 4,5 In recent years, large-scale clinical trials have confirmed that TCM has made progress in controlling blood glucose levels. Additionally, the application of modern science and technology has helped to uncover some of the therapeutic mechanisms underlying TCM's potency. Studies have been conducted to *Jiaxing Tian, De Jin and Fengmei Lian contributed equally to this study. Fengmei Lian and Xiaolin Tong are co-corresponding authors.