Switching to once-weekly insulin icodec versus once-daily insulin glargine U100 in individuals with basal-bolus insulin-treated type 2 diabetes (ONWARDS 4): a phase 3a, randomised, open-label, multicentre, treat-to-target, non-inferiority trial

Background: Insulin icodec (icodec) is a basal insulin analogue suitable for once-weekly dosing. ONWARDS 4 aimed to assess the efficacy and safety of once-weekly icodec compared with once-daily insulin glargine U100 (glargine U100) in individuals with long-standing type 2 diabetes on a basal-bolus regimen.

Methods: In this 26-week, phase 3a, randomised, open-label, multicentre, treat-to-target, non-inferiority trial, adults from 80 sites (outpatient clinics and hospital departments) across nine countries (Belgium, India, Italy, Japan, Mexico, the Netherlands, Romania, Russia, and the USA) with type 2 diabetes (glycated haemoglobin [HbA_1c] 7·0-10·0%) were randomly assigned (1:1) to receive once-weekly icodec or once-daily glargine U100 combined with 2-4 daily bolus insulin aspart injections. The primary outcome was change in HbA_1c from baseline to week 26 (non-inferiority margin of 0·3 percentage points). The primary outcome was evaluated in the full analysis set (ie, all randomly assigned participants). Safety outcomes were evaluated in the safety analysis set (ie, all participants randomly assigned who received at least one dose of trial product). This trial is registered with ClinicalTrials.gov, NCT04880850.

Findings: Between May 14 and Oct 29, 2021, 746 participants were screened for eligibility, of whom 582 (78%) were randomly assigned (291 [50%] to icodec treatment and 291 [50%] to glargine U100 treatment). Participants had a mean duration of type 2 diabetes of 17·1 years (SD 8·4). At week 26, estimated mean change in HbA_1c was -1·16 percentage points in the icodec group (baseline 8·29%) and -1·18 percentage points in the glargine U100 group (baseline 8·31%), showing non-inferiority for icodec versus glargine U100 (estimated treatment difference 0·02 percentage points [95% CI -0·11 to 0·15], p<0·0001). Overall, 171 (59%) of 291 participants in the icodec group and 167 (57%) of 291 participants in the glargine U100 group had an adverse event. 35 serious adverse events were reported in 22 (8%) of 291 participants in the icodec group and 33 serious adverse events were reported in 25 (9%) of 291 participants receiving glargine U100. Overall, combined level 2 and level 3 hypoglycaemia rates were similar between treatment groups. No new safety concerns were identified for icodec.

Interpretation: In people with long-standing type 2 diabetes on a basal-bolus regimen, once-weekly icodec showed similar improvements in glycaemic control, with fewer basal insulin injections, lower bolus insulin dose, and with no increase in hypoglycaemic rates compared with once-daily glargine U100. Key strengths of this trial include the use of masked continous glucose monitoring; the high trial completion rate; and the inclusion of a large, diverse, and multinational population. Limitations include the relatively short trial duration and the open-label design.

Funding: Novo Nordisk.