OBJECTIVES: In patients with type-1 diabetes, poor glycemic control is associated with increased risk of complications. A recent clinical study provided evidence that basal/bolus treatment with insulin detemir+insulin aspart (IDet/IAsp) improved HbA1c (0.22%-points lower after 18 weeks), reduced risk of hypoglycemic events (by 21%), and decreased body mass index (BMI) (-0.3 kg.m-2) in comparison to neutral protamine Hagedorn insulin+human soluble insulin (NPH/HSI). The aim of this study was to evaluate the long-term impact of these short-term clinical benefits in patients with type-1 diabetes in the Dutch setting. METHODS: We used a validated computer simulation model (CORE Diabetes Model) to project long-term clinical and cost outcomes in patients receiving IDet/IAsp or NPH/HSI based on the clinical study findings. Standard Markov sub-models were combined to simulation the incidence and progression of complications (cardiovascular disease, neuropathy, renal and eye disease). Transition probabilities and HbA1c-dependent adjustments were derived from published sources. Baseline cohort characteristics and treatment effect data were based on the clinical study. Direct costs were retrieved from published sources and projected over patient lifetimes from a Dutch National Health Care perspective. Costs and clinical benefits were discounted at 4% per annum. RESULTS: IDet/IAsp treatment was associated with fewer diabetes-related complications, improved life expectancy (0.15 life years gained) and quality-adjusted life expectancy (0.10 QALYs gained) compared to NPH/HSI. Mean total lifetime costs were 872€ per patient higher with IDet/IAsp, leading to incremental cost-effectiveness ratios (ICERs) of 5813€ per life year and 8720€ per QALY gained. CONCLUSION: Short-term clinical benefits in glycemic control, hypoglycemic event rates and BMI associated with IDet/IAsp basal/bolus therapy were projected to lead to fewer complications, and improved life expectancy and quality-adjusted life expectancy over patient lifetimes compared to NPH/HSI. This resulted in ICERs for IDet/IAsp versus NPH/HSI in the range considered to represent excellent value for money.