Semaglutide 2·4 mg once a week in adults with overweight or obesity, and type 2 diabetes (STEP 2): a randomised, double-blind, double-dummy, placebo-controlled, phase 3 trial

Background: This trial assessed the efficacy and safety of the GLP-1 analogue once a week subcutaneous semaglutide 2·4 mg versus semaglutide 1·0 mg (the dose approved for diabetes treatment) and placebo for weight management in adults with overweight or obesity, and type 2 diabetes.

Methods: This double-blind, double-dummy, phase 3, superiority study enrolled adults with a body-mass index of at least 27 kg/m² and glycated haemoglobin 7-10% (53-86 mmol/mol) who had been diagnosed with type 2 diabetes at least 180 days before screening. Patients were recruited from 149 outpatient clinics in 12 countries across Europe, North America, South America, the Middle East, South Africa, and Asia. Patients were randomly allocated (1:1:1) via an interactive web-response system and stratified by background glucose-lowering medication and glycated haemoglobin, to subcutaneous injection of semaglutide 2·4 mg, or semaglutide 1·0 mg, or visually matching placebo, once a week for 68 weeks, plus a lifestyle intervention. Patients, investigators, and those assessing outcomes were masked to group assignment. Coprimary endpoints were percentage change in bodyweight and achievement of weight reduction of at least 5% at 68 weeks for semaglutide 2·4 mg versus placebo, assessed by intention to treat. Safety was assessed in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, NCT03552757 and is closed to new participants.

Findings: From June 4 to Nov 14, 2018, 1595 patients were screened, of whom 1210 were randomly assigned to semaglutide 2·4 mg (n=404), semaglutide 1·0 mg (n=403), or placebo (n=403) and included in the intention-to-treat analysis. Estimated change in mean bodyweight from baseline to week 68 was -9·6% (SE 0·4) with semaglutide 2·4 mg vs -3·4% (0·4) with placebo. Estimated treatment difference for semaglutide 2·4 mg versus placebo was -6·2 percentage points (95% CI -7·3 to -5·2; p<0·0001). At week 68, more patients on semaglutide 2·4 mg than on placebo achieved weight reductions of at least 5% (267 [68·8%] of 388 vs 107 [28·5%] of 376; odds ratio 4·88, 95% CI 3·58 to 6·64; p<0·0001). Adverse events were more frequent with semaglutide 2·4 mg (in 353 [87·6%] of 403 patients) and 1·0 mg (329 [81·8%] of 402) than with placebo (309 [76·9%] of 402). Gastrointestinal adverse events, which were mostly mild to moderate, were reported in 256 (63·5%) of 403 patients with semaglutide 2·4 mg, 231 (57·5%) of 402 with semaglutide 1·0 mg, and 138 (34·3%) of 402 with placebo.

Interpretation: In adults with overweight or obesity, and type 2 diabetes, semaglutide 2·4 mg once a week achieved a superior and clinically meaningful decrease in bodyweight compared with placebo.

Funding: Novo Nordisk.