OBJECTIVES: Patients with type 2 diabetes typically use several drug treatments during their lifetime. Research is needed to assess the cost-effectiveness of second-line therapy of antidiabetic drugs after metformin monotherapy failure. The objective of this study was to evaluate the long-term cost-effectiveness of dipeptidyl peptidase-4 inhibitors (DPP-4i) and sulfonylureas (SU) as second-line therapy in combination with metformin from the US third-party payer perspective.

METHODS: A Markov model with four health states, one-year cycles and 25-years time horizon was developed. Patients were assumed to initiate metformin monotherapy at age 60. Outcomes and cost data were collected from previous published studies and other secondary data sources. The incremental cost-effectiveness ratio (ICER) and the net monetary benefit (NMB) for different willingness to pay (WTP) per life-year were estimated. Costs and outcomes were discounted at a 3% annual rate. One-way and probabilistic sensitivity analyses were performed in the study.

RESULTS: Patients in the metformin+DPP-4i treatment pathway had $18,830 in discounted diabetic-related costs and 12.42 discounted life-years. Metformin+SU was associated with discounted costs of $6,995 per patient and 11.81 discounted life-years. Comparing metformin+DPP-4i and metformin+SU treatment pathways, the discounted incremental costs was $11,835 and the discounted incremental life years were 0.61, resulting in the ICER of $19,477 per life-year gained for patients using the metformin+DPP-4i treatment pathway. The average results of the probabilistic analysis yielded $11,772 discounted incremental costs and 0.59 incremental discounted life-years gained for patients using metformin+DPP-4i compared to the metformin+SU treatment pathway, with an ICER of $19,836 per life-year gained.

CONCLUSIONS: Metformin+DPP-4i was cost-effective as the second-line therapy in comparison with metformin+SU from the US health care payer perspective. The results were not sensitive to changes in the parameters used in the study. More studies assessing the cost-effectiveness of alternative type 2 diabetes treatment pathways are needed.