OBJECTIVES: Type-2 diabetes is a major health problem. 30% of all patients being on dialysis suffer from a diabetic Endstage Renal Disease (ESRD). The Angiotensin-2-Receptor-Blocker (ARB) Irbesartan has proven its capability to prevent or delay an ESRD. Based on the results of the multicentre double-blind, randomized, placebo-controlled Irbesartan Diabetic Nephropathy Trial (IDNT) the presented study aims to show that a treatment of renal diseases in hypertensive type-2 diabetics with the ARB Irbesartan is cost saving for the German health care system. METHODS: A cost-effectiveness analysis from the German payers’ perspective was conducted taking direct costs into account. 1715 type-2 diabetics with hypertension and limited renal function were included in IDNT (2.6 years, subgroup with 300 mg/d Irbesartan). The patient number needed to treat (NNT) to prevent one ESRD was the efficacy parameter for this analysis. Public sources were used for cost data and information on dialysis and transplantation in diabetics with ESRD. Actual drug prices were used taking into account discounts and co-payments effective in Germany due to new legislation since January 2004. Due to conservative calculation no discounting was performed, follow-up treatment costs were not included. RESULTS: The NNT for the primary endpoint ESRD calculated to 28 during the study period of 2.6 years in IDNT. That means additional treatment costs of €25,007.- lead to one prevented ESRD (incremental cost-effectiveness-ratio). The prevented ESRD (82% dialysis, 18% transplantation) is worth €45,766.- which shows a benefit for Irbesartan treatment of €20,758.- after 2.6 years or €7,984.- per year assuming a linear trend towards delay in ESRD. A sensitivity analysis stated the robustness of the data. CONCLUSIONS: Based on epidemiologic data our results suggest savings for the German health care system of €3.2 billion after 2.6 years if annually additional €681 million were invested in the treatment of type-2 diabetics with Irbesartan.