OBJECTIVES: The Economic Assessment of Glycemic control and Long-term Effects (EAGLE) model version 2.0 simulates long-term diabetes-related complications and related costs for type 1 and type 2 diabetes using equations derived from the published results of several large interventional studies (DCCT, WESDR, and UKPDS). To assess the model's validity, EAGLE was internally validated according to current guidelines. METHODS: Following in-house testing protocols, first-order validation identified inconsistencies in results and corrected programming errors. Second-order validation involved the following steps: 1) Simulation sets were created in EAGLE based on baseline data from the studies used to build the model; 2) Simulations were run. The results obtained with EAGLE were compared with the published event rates; and 3) Risk equations were refined if a deviation of >10% was observed between the model-derived and published results. Patient numbers and iterations were systematically changed until a final run was performed with 50,000 patients and 100 iterations. RESULTS: Fulfilling a criterion for validity, the cumulative incidence per 1000 patient-years and incidence rates for all events simulated with EAGLE fell within the range of ±10%. The difference between published data and model results ranged from 0% to 9% for all patient populations after possible refinements. For example, in type 2 diabetes, EAGLE successfully predicted the end-stage renal disease and fatal event rates reported in UKPDS (deviation = 0%). The rates of severe hypoglycemia differed by 1%. The EAGLE event rates for proliferative and nonproliferative retinopathy corresponded well with event rates derived from the WESDR publications (deviation = 3% and 4%, respectively). CONCLUSIONS: EAGLE consistently predicts event rates reported by UKPDS, WESDR, and DCCT, and is thus a valid and robust tool for the analysis of the long-term diabetes-related complications and related costs in type 1 and type 2 diabetes.