RCT selection
The study selection process is depicted in Figure 1 . Finally, seven independent, double-blind, randomized, controlled trials (a total of 762 patients) were included in the current meta-analysis14,15,19-23. All the seven trials were of high quality with modified Jadad scores≄ 4. The seven trials are multi-center clinical trials, among which 3 of them14,19,21 are transnational multicenter trials. The category of GKA is different among the 7 trials, including MK-094114, AZD165619, LY259950620, PF-0493731921, RO438962022, HMS555223, and TTP39915. In addition, all these 7 studies use identification of HbA1c as a criterion for patient inclusion, and the absence of glutamic acid decarboxylation antibody at admission is used to exclude patients with type 1 diabetes. All 7 trials are placebo-controlled. The details of the included studies are summarized in Table 1 . Details of the modified Jadad scale for each study are provided in Supplementary Table 2.