OBJECTIVES: To project the cumulative incidence of end-stage renal disease (ESRD), life expectancy and costs in Taiwan of treating patients with diabetes, hypertension, and microalbuminuria (DHM) with either standard hypertension treatment alone or standard hypertension treatment plus irbesartan 300 mg daily. METHODS: A peer-reviewed, published Markov model that simulated progression from microalbuminuria to nephropathy, doubling of serum creatinine, ESRD, and all-cause mortality in patients with DHM was adapted to Taiwan. Three strategies were compared: A) early use of irbesartan (i.e. start treatment in subjects with microalbuminuria) versus B) late use of irebesartan (i.e. as from overt nephropathy), or C) standard hypertension care (with comparable blood pressure control). Cumulative incidence of ESRD, costs and life expectancy were projected for a hypothetical cohort of 1000 subjects. Treatment-specific progression and mortality probabilities were derived from published trials: IRMA-2 (in microalbuminuria) and IDNT (in overt nephropathy). Medical management and cost data per state were obtained from published local sources. A flexible time horizon up to 25-years and third party payer perspective were used. Future costs and LE were discounted at 3% yearly. RESULTS: When compared to standard blood pressure control, early irbesartan was projected to reduce the cumulative incidence of ESRD from (mean±standard deviation) 22% to 8%, save TN$248,302 (US$7,303), and add 0.702 life years per treated patient. Late irbesartan was dominant to control but dominated by early irbesartan. The superiority of early use of irbesartan over standard care was robust for most variables, except for the cost of dialysis and the time horizon. Break-even occurred after 12 years. CONCLUSIONS: Treating DHM patients with early irbesartan was projected to reduce the incidence of ESRD, extend life and reduce costs. Treating patients at a later stage is still beneficial, however to a lower extent. Applying flexible time horizons shows additional relevant information to decision makers.