ObjectiveTo systematically review the efficacy and safety of laparoscopic Roux-en-Y gastric bypass (LRYGB) versus laparoscopic sleeve gastrectomy (LSG) for obesity and type 2 diabetes mellitus (T2DM). MethodsWe searched PubMed, EMbase, The Cochrane Library (Issue 8, 2014), CNKI and WanFang Data from inception to December 2014, to collect randomized controlled trials (RCTs) of LRYGB vs. LSG for obesity and T2DM. Two reviewers independently screened literature, extracted data and evaluated the risk of bias of included studies. Then, meta-analysis was performed using RevMan 5.2 software. ResultsA total of 8 RCTs including 828 patients were included. The results of meta-analysis showed that:There were no significant differences between the LRYGB group and the LSG group in body mass index (MD=-1.02, 95%CI -2.90 to 0.86, P=0.29), remission rate of T2DM (OR=1.11, 95%CI 0.71 to 1.73, P=0.64), reoperation rate (OR=2.74, 95%CI 1.01 to 7.42, P=0.05), level of fasting plasma glucose (MD=2.71, 95%CI -0.80 to 6.21, P=0.13), and level of serum low density lipoprotein (MD=-23.85, 95%CI -47.20 to -0.50, P=0.05). However, the LSG group had lower postoperative complication rate (OR=2.28, 95%CI 1.43 to 3.62, P=0.000 5) than that of the LRYGB group. ConclusionIn short term, both LRYGB and LSG were equally efficient in the treatment of obesity and T2DM, but LSG has lower postoperative complication rate than LRYGB. Due to the limited quality and quantity of the included studies, more high quality studies are needed to verify the above conclusion.