The efficacy and safety of liraglutide added to metformin in patients with diabetes: a meta-analysis of randomized controlled trials

Liraglutide, a glucagon-like peptide (GLP-1) receptor agonist, has showed favorable effects in the glycaemic control and weight reduction in patients with type 2 diabetes mellitus (T2DM). The meta-analysis was to compare the efficacy and safety of liraglutide added to metformin with other treatments in patients with T2DM. A systematic literature search on PubMed, Embase, Web of Science and the Cochrane library databases were performed. Eligible studies were randomized controlled trials (RCTs) of patients with T2DM who received the combination treatment of liraglutide and metformin. Pooled estimates were performed using a fixed-effects model or random-effects model. A total of nine RCTs met the inclusion criteria. Compared with control (placebo, sitagliptin, glimepiride, dulaglutide, insulin glargine, and NPH), liraglutide in combination with metformin resulted in significant reductions in HbA1c, bodyweight, FPG, and PPG, and similar reductions in SBP, and DBP. Moreover, liraglutide combined with metformin did not increase the risk of hypoglycemia, but induced a higher incidence of gastrointestinal disorders. In conclusion, this meta-analysis confirmed the use of liraglutide as add-on to metformin appeared to be effective and safe for patients with T2DM. However, considering the potential limitations in this study, more large-scale, well-conducted RCTs are needed to identify our findings.