OBJECTIVES: This post-hoc analysis estimated the budget impact of PHEN/TPM ER 7.5/46 mg in comparison with lifestyle modification (LM) alone in overweight and obese patients with comorbid prediabetes or T2DM.   METHODS: A 1-year budget impact model was developed from the health plan perspective evaluating pharmacy costs and comorbidity costs in overweight and obese patients with prediabetes or T2DM. Changes in body mass index (BMI) for PHEN/TPM ER 7.5/46 and LM were based on data from CONQUER, a phase 3, 56-week randomized trial (Gadde 2011). Comorbidity cost offsets for BMI reductions were calculated by multiplying the change in BMI by medical ($164) and pharmacy ($113) costs per unit of BMI (Wang 2006). The rate of progression from prediabetes to T2DM was based on data from CONQUER. Literature-based estimates of the annual cost of treating prediabetes ($535) and T2DM ($8069) were used to calculate comorbidity costs. The plan population was assumed to be 1,000,000 patients and the market uptake of PHEN/TPM ER 7.5/46 was assumed to be 1% at a weighted cost per capsule of $5.04. RESULTS: In patients with prediabetes, BMI was reduced by 4.30kg/m for PHEN/TPM ER 7.5/46 and 2.15kg/m for LM, translating to annual cost offsets of $1191 and $596, respectively. The rate of progression from prediabetes to T2DM was 3.8% for PHEN/TPM ER and 9.6% for LM. In patients with T2DM, the BMI reduction was 3.69kg/m for PHEN/TPM ER and 1.96kg/m for LM, translating to cost offsets of $1022 and $543, respectively. The budget impact of adding PHEN/TPM ER 7.5/46 therapy was $0.01 per member per month (PMPM) for prediabetes and $0.05 PMPM for T2DM. CONCLUSIONS: The budget impact of adding weight management therapy with PHEN/TPM ER in overweight or obese patients with prediabetes or T2DM is minimal and is offset by reduced comorbidity costs.