Background:The efficacy and safety of once-weekly dipeptidyl peptidase-4 inhibitor (DPP-4i) omarigliptin as monotherapy or add on to other antihyperglycemic agents (AHAs) in patients with type 2 diabetes mellitus (T2DM) is unclear.Methods:PubMed, EMBASE, Cochrane library, and ClinicalTrials.gov were searched from the inception to January 24, 2018. Randomized controlled trials comparing omarigliptin with placebo or other AHAs in T2DM patients were included in our meta-analysis. Risk ratio (RR) and mean difference (MD) were used to evaluate the outcomes.Results:Totally, 11 trials involving 8276 patients were satisfied with our inclusion criteria. Compared with control group, omarigliptin was associated with a significantly stronger reduction in hemoglobin A1c (HbA1c) (MD 0.38%, 95% confidence interval [CI] [0.18, 0.58], P = .0002) and fasting plasma glucose (MD 0.48 mmol/L, 95% CI [0.14 mmol/L, 0.82 mmol/L], P = .006). Omarigliptin increased the number of participants who achieved HbA1c < 7.0% compared with control group (RR 2.03, 95% CI [1.38, 2.98], P = .0003). No significant difference was found in the aspect of adverse events (RR 1.00, 95% CI [0.97, 1.03], P = .99), serious adverse events (RR 1.02, 95% CI [0.91, 1.13], P = .75), hypoglycemic events (RR 0.86, 95% CI [0.48, 1.54], P = .61) between omarigliptin and control group. Omarigliptin has a homologous efficacy and safety background to other AHAs according to the results of subgroup analysis.Conclusions:This review revealed that omarigliptin had a favorable efficacy and safety as monotherapy or add on to other AHAs in treating T2DM patients. It is a superior choice for T2DM patients who have a poor adherence to daily AHAs.