BACKGROUND: Oral semaglutide was approved in 2019 for blood glucose control in patients with type 2 diabetes mellitus (T2DM) and was the first oral glucagon-like peptide 1 receptor agonist (GLP-1 RA). T2DM is associated with substantial healthcare expenditures in the US, so the cost of a new intervention should be weighed against clinical benefits. OBJECTIVE: This study evaluated the budget impact of a treatment pathway with oral semaglutide 14 mg daily versus oral sitagliptin 100 mg daily among patients not achieving target glycated hemoglobin (HbA1c) level despite treatment with metformin. METHODS: This study used the validated IQVIA™ CORE Diabetes Model to simulate the treatment impact of oral semaglutide 14 mg and sitagliptin 100 mg over a 5-year time horizon from a US healthcare sector (payer) perspective. Trial data (PIONEER 3) informed cohort characteristics and treatment effects, and literature sources informed event costs. Population and market share data were from the literature and data on file. The analysis evaluated the estimated budget impact of oral semaglutide 14 mg use for patients currently using sitagliptin 100 mg considering both direct medical and treatment costs to understand the impact on total cost of care, given underlying treatment performance and impact on avoidable events. RESULTS: In a hypothetical plan of 1 million lives, an estimated 1993 patients were treated with sitagliptin 100 mg in the target population. Following these patients over 5 years, the incremental direct medical and treatment costs of a patient using oral semaglutide 14 mg versus sitagliptin 100 mg was $US16,562, a 70.7% increase (year 2019 values). A hypothetical payer would spend an additional $US3,300,143 (7.1%) over 5 years for every 10% of market share that oral semaglutide 14 mg takes away from sitagliptin 100 mg. Univariate and scenario analyses with alternate inputs and assumptions demonstrated consistent results. CONCLUSIONS: Use of oral semaglutide 14 mg in patients currently receiving sitagliptin 100 mg substantially increases the budget impact for patients with T2DM whose blood glucose level is not controlled with metformin over a 5-year time horizon for US healthcare payers.