AIMS: To assess the efficacy and safety of semaglutide, a recently approved glucagon-like peptide 1 receptor agonist (GLP-1 RA) for type 2 diabetes.MATERIALS AND METHODS: We searched major electronic databases and grey literature sources for randomized controlled trials comparing semaglutide with placebo or other antidiabetic agents. Primary outcome was change from baseline in HbA1c. Secondary endpoints included change from baseline in body weight, blood pressure, heart rate and incidence of hypoglycaemia, gastrointestinal adverse effects, pancreatitis and diabetic retinopathy.RESULTS: A total of 6 placebo-controlled and 7 active-controlled studies with subcutaneous semaglutide were included. We identified only 1 trial with oral semaglutide. Compared with placebo, subcutaneous semaglutide 0.5 and 1 mg reduced HbA1c by 1.01% (95% CI, 0.56-1.47) and 1.38% (1.05-1.70), respectively. Both doses demonstrated superior glycaemic efficacy compared to other antidiabetic agents, including sitagliptin, exenatide, liraglutide, dulaglutide and insulin glargine. Semaglutide also had a beneficial effect on body weight (mean difference vs placebo -4.11 kg, 95% CI -4.85 to -3.37 for semaglutide 1 mg) and systolic blood pressure. We did not observe increased hypoglycaemia rates with semaglutide; nevertheless, we noted an increased incidence of nausea, vomiting and diarrhoea. Cases of pancreatitis were infrequent and the odds ratio for diabetic retinopathy compared with placebo was 1.32 (95% CI, 0.98-1.77).CONCLUSIONS: Semaglutide is a potent once-weekly GLP-1 RA, significantly reducing HbA1c, body weight and systolic blood pressure. However, it is associated with increased incidence of gastrointestinal adverse events. Results for pancreatitis and retinopathy require further assessment in post-approval pharmacovigilance studies.