OBJECTIVE - The Diabetes Care Protocol (DCP), a multifaceted Computerized decision support diabetes management intervention, reduces cardiovascular risk Of type 2 diabetic patients. We performed a cost-effectiveness analysis of DCP from a Dutch health care perspective. RESEARCH DESIGN AND METHODS - A cluster randomized trial provided data of DCP versus usual care. The I-year follow-up patient data were extrapolated using a modified Dutch microsimulation diabetes model, computing individual lifetime health-related costs, and health effects. incremental costs and effectiveness (quality-adjusted life-years [QALYs]) were estimated using multivariate generalized estimating equations to correct for practiice-level clustering and confounding. Incremental cost-effectiveness ratios (ICERs) were calculated and cost-effectiveness acceptability curves were created. Stroke costs were calculated separately. Subgroup analyses examined patients with and without cardiovascular disease (CVD+ or CVD-patients, respectively). RESULTS - Excluding Stroke, DCP patients lived longer (0.14 life-years, P = NS), experienced more QALYs (0.037, P = NS), and incurred higher total costs ((sic)1,415, P = NS), resulting in an ICER of (sic)38,243 per QALY gained. The likelihood Of Cost-effectiveness given a willingness-to-pay threshold of (sic)20,000 per QALY gained is 30%. DCP had a more favorable effect on CVD+ patients (ICER = (sic)14,814) than for CVD - Patients (ICER = (sic)121,285). Coronary heart disease costs were reduced ((sic)-587, P < 0.05). CONCLUSIONS - DCP reduces cardiovascular risk, resulting in only a slight improvement in QALYs, lower CVD costs, but higher total costs, With a high cost-effectiveness ratio. Cost-effective care can be achieved by focusing on cardiovascular risk factors in type 2 diabetic patients with a history of CVD.