Abstract: Objective To systematically evaluate the effect of ketogenic diet on blood glucose control, weight management and lipid metabolism indexes in patients with type 2 diabetes mellitus(T2DM). Methods In this study, the databases such as PubMed, EMBASE, Cochrane Library and CNKI were used to search for randomized controlled trials of ketogenic diet in the treatment of T2DM. We set the inclusion and exclusion criteria and the quality of the literature was evaluated according to the assessment criteria of Cochrane bias risk. We used RevMan5.3 for the Meta-analysis, and the subgroup analysis of intervention time was carried out for the results with higher heterogeneity. Results A total of 9 studies with 695 T2DM patients were included. (1) Compared with the controlled diets, ketogenic diet led to greater reductions in fasting plasma glucose(MD=-0.22, 95%CI was -0.29 to -0.15, P<0.001), fasting insulin(MD=-1.23, 95%CI was -1.89 to -0.57, P=0.003)and insulin resistance index(MD=-0.10, 95%CI was -0.20 to 0.01, P=0.03). (2) The results of subgroup analysis showed that ketogenic diet significantly decreased glycosylated hemoglobin - (MD=-0.41, 95%CI was -0.46 to -0.35, P<0.001), body weight(MD=-2.46, 95%CI was -3.98 to -0.94, P=0.002)and body mass index(MD=-3.07, 95%CI was -3.77 to -2.37, P<0.001)when the intervention time was less than or equal to 6 months. There was no significant difference in the indexes mentioned above between the two groups when the intervention time was more than 6 months(P>0.05). (3) Ketogenic diet for more than 6 months effectively reduced triglyceride(MD=-0.36, 95%CI was -0.49 to -0.22, P<0.001)and increased high density lipoprotein cholesterol(MD=0.09, 95%CI was 0.02 to 0.17, P=0.02), but it was not as good as control diet in reducing total cholesterol(MD=0.11, 95%CI was 0.01 to 0.20, P=0.03)and low density lipoprotein cholesterol(MD=0.14, 95%CI was 0.03 to 0.24, P=0.01). Conclusion Short-term ketogenic diet can significantly improve glucose metabolism and reduce body weight and body mass index in T2DM patients, but its long-term effect is not obvious. Long-term ketogenic diet can reduce triglyceride and increase high density lipoprotein cholesterol, but shows no effects on total cholesterol and low density lipoprotein cholesterol. For a long period of time, a stereotype is rooted in people's mind that diabetes is a chronic progressive disease requiring long-term drug or insulin treatment in domestic and foreign academic circles. The greatest academic value of ketogenic diet intervention is that it breaks through the stereotype, and makes it possible to treat and prevent diabetes by a new lifestyle intervention.