ObjectivesTo systematically review the therapeutic efficacy of vitamin B1 for adjunctive treatment in type 2 diabetes mellitus.MethodsDatabases including PubMed, EMbase, The Cochrane Library, CNKI, VIP, WanFang Data and CBM were searched to collect randomized controlled trials (RCTs) on vitamin B1 for adjunctive treatment in type 2 diabetes mellitus from inception to July 2017. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Then, meta-analysis was conducted by RevMan 5.3 and Stata 12.0 softwares. ResultsA total of 6 RCTs involving 346 patients were included. The results of meta-analysis showed that, compared with the control group, the vitamin B1 adjunctive group had a significant improvement in CRP (MD=–1.09, 95%CI –1.63 to –0.54, P<0.000 1). However, the fasting blood glucose (MD=–0.23, 95%CI –0.58 to 0.13,P=0.22), glycosylated hemoglobin (MD=0.13, 95%CI –0.25 to 0.52, P=0.49), 2 hours plasma glucose (MD=–0.18, 95%CI –1.03 to 0.67, P=0.68), systolic pressure (MD=2.94, 95%CI –1.31 to 7.18, P=0.18), diastolic pressure (MD=–1.60, 95%CI –4.24 to 1.05, P=0.24), triglycerides (MD=–0.12, 95%CI –0.32 to 0.09, P=0.27), total cholesterol (MD=0.21, 95%CI –0.05 to 0.46, P=0.12), high-density lipoprotein cholesterols (MD=0.03, 95%CI –0.07 to 0.12, P=0.56) and low-density lipoprotein cholesterols (MD=0.12, 95%CI –0.11 to 0.35, P=0.30) had no significant differences between both groups.ConclusionsVitamin B1 adjunctive treatment could not improve the levels of blood glucose, blood pressure and serum lipids. Due to limited quality and quantity of the included studies, more high quality studies are required to verify above conclusions.