OBJECTIVES: To evaluate the long-term cost-effectiveness of switching from basal insulin to biphasic insulin aspart 30 (BIAsp30) in patients with type 2 diabetes (T2D) in China. METHODS: A published and validated computer simulation model of diabetes (CORE Diabetes Model) was used to project long-term (30 years) of health and economic outcomes. Simulated cohorts and treatment effects were derived from a 16-week, multi-centre, and single-arm trial-NCT00669864 which investigated the efficacy and safety of BIAsp30 ± Metformin in T2D patients inadequately controlled with basal insulin. Two subgroups of basal insulin treatment were categorized as insulin glargine (IGla) ± Metformin and neutral protamine hagedorn (NPH) insulin ± Metformin. The market retail prices of medications were calculated to estimate treatment costs. The diabetes management and complications costs were obtained from Chinese published data. An annual discounting rate of 3% was used for both costs and health outcomes. One-way sensitivities analysis was performed. RESULTS: Therapy conversion to BIAsp30 was projected to improve life expectancy significantly in comparison with IGla (0.347±0.245 years), and NPH (0.452±0.242 years). Transfer to BIAsp30 was associated with improvements in 0.327 quality-adjusted life years (QALYs) over IGla, and 0.393 QALYs over NPH. Therapy conversion to BIAsp30 reduced medical costs by Chinese Yuan (CNY) 46,540 per patient compared to IGla. However, it increased CNY 19,525 compared to NPH and was associated with an incremental cost-effectiveness ratio of CNY 49,730 per QALY gained. CONCLUSIONS: Therapy conversion from basal insulin to BIAsp30 in T2D patients in China was associated with improvements in life expectancy and QALYs. Transfer to BIAsp30 was cost-saving treatment strategy in T2D patients managed with IGla, and would be considered cost-effective in T2D patients managed with NPH, given a willingness-to-pay threshold of CNY 75,375 per QALY (3 times GDP per capita in 2009) gained in China.