AimsOnce-weekly semaglutide and dulaglutide represent two highly efficacious treatment options for type 2 diabetes. A recent indirect treatment comparison (ITC) has associated semaglutide 1 mg with similar and greater improvements in glycated haemoglobin (HbA1c) and body weight, respectively, vs. dulaglutide 3 mg and 4.5 mg. The present study aimed to evaluate the long-term cost-effectiveness of semaglutide 1 mg vs. dulaglutide 3 mg and 4.5 mg in the UK.Materials and methodsThe IQVIA CORE Diabetes Model (v9.0) was used to project outcomes over patients’ lifetimes. Baseline cohort characteristics were sourced from SUSTAIN 7, with changes in HbA1c and body mass index applied as per the ITC. Modelled patients received semaglutide or dulaglutide for 3 years, after which treatment was intensified to basal insulin. Costs (expressed in 2020 pounds sterling [GBP]) were accounted from a healthcare payer perspective.ResultsSemaglutide 1 mg was associated with improvements in quality-adjusted life expectancy of 0.05 and 0.04 quality-adjusted life years (QALYs) vs. dulaglutide 3 mg and 4.5 mg, respectively, due to a reduced incidence of diabetes-related complications with semaglutide. Direct costs were estimated to be GBP 76 lower and GBP 8 higher in the comparisons with dulaglutide 3 mg and 4.5 mg, respectively. Overall outcomes were similar, but favoured semaglutide, and based on modelled mean outcomes it was considered dominant vs. dulaglutide 3 mg and associated with an incremental cost-effectiveness ratio of GBP 228 per QALY gained vs. dulaglutide 4.5 mg.ConclusionsSemaglutide 1 mg represents a cost-effective treatment vs. dulaglutide 3 mg and 4.5 mg for type 2 diabetes from a healthcare payer perspective in the UK.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10198-022-01514-1.