As sodium–glucose cotransporter-2 inhibitors (SGLT-2is) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) are second-line treatment options in type 2 diabetes mellitus (T2DM), our study sought to provide precise effect estimates regarding the role of GLP-1RAs vs SGLT-2is as add-on treatments in patients uncontrolled by metformin monotherapy.

PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL) and ‘grey literature’ were searched from their inception up to December 2019 for randomized controlled trials (RCTs) with durations≥12weeks to evaluate the safety and efficacy of adding a GLP-1RA vs an SGLT-2i in patients with T2DM.

Three eligible RCTs were identified. Administration of GLP-1RAs vs SGLT-2is resulted in significant decreases in HbA1c with no significant impact on either body weight or fasting plasma glucose. GLP-1RA treatment led to a significant increase in odds for achieving an HbA1c<7% compared with SGLT-2is, whereas no difference was detected in body weight reductions of>5%. Significantly greater risk for any hypoglycaemia, nausea and diarrhoea, and lower risk for genital infections, was also observed with GLP-1RAs, while no differences regarding severe hypoglycaemia, treatment discontinuation and impact on blood pressure levels were identified. No other major safety issues arose.

Our meta-analysis suggests that GLP-1RAs provide better glycaemic effects than SGLT-2is in patients with T2DM uncontrolled by metformin, albeit while increasing risk for hypoglycaemia and gastrointestinal adverse events.