OBJECTIVES: Diabetes affects over 2.3 million people in UK; approximately 10% have type 1 diabetes (T1DM). The aim of this study was to evaluate the long-term cost and clinical outcomes associated with lispro versus regular human insulin (RHI) in the UK T1DM patients using the previously published and validated CORE Diabetes Model. METHODS: Several clinical trials have provided evidence that short-acting insulin analogs, with improved pharmacokinetic properties, may have benefits in terms of glycaemic control (HbA1c) and hypoglycemic event rates compared to mealtime human insulin. For the simulations, clinical benefits were derived from a recent Cochrane meta-analysis which found the weighted mean difference in HbA1c to be -0.1% (95% CI -0.2% to -0.0%) for treatment with lispro versus RHI. Major hypoglycaemic event rates for lispro and RHI were 21.8 and 46.1 per 100 patient-years, respectively. Current prices of insulin lispro (Humalog), regular human insulin (Humulin R) and basal NPH insulin (Humulin I) were obtained from www.mims.co.uk. Complication costs and patient management costs (screening and concomitant medications) were derived from published sources. All costs were accounted in 2007 Pounds Sterling (£) from a National Health Service (NHS) perspective. Future costs and clinical benefits were discounted at 3.5% annually. RESULTS: Model projections indicated that lispro was associated with a benefit in quality-adjusted life expectancy of approximately 0.10 QALYS versus RHI (7.60 versus 7.50 QALYs). Lifetime direct medical costs per patient were lower with lispro treatment, £70,576 versus £72,529. Lispro was projected to be dominant (lower cost: more benefit) compared to RHI. Results were robust to sensitivity analyses including time horizon, discounting rates and scenarios assuming benefit only on glycaemic control or hypoglycemia rates. CONCLUSIONS: The study suggests that lispro is likely to improve quality-adjusted life expectancy and reduce costs in UK patients with T1DM, due principally to benefits in hypoglycemic event rates.