Education and training in self-management of blood glucose control has become a permanent task for all people involved in the care of diabetic patients. Since this may be facilitated by applying state-of-the-art information technology, we have developed the decision support system KADIS (Karlsburg Diabetes Management System). It comprises computer-aided tools for (1) the evaluation (selection, aggregation, storage, statistics, graphics) of therapeutic data, e.g. from patients' logbooks, and (2) the simulation of daily profiles of glycaemia and insulinaemia on the basis of a mathematical model of the glucose-insulin regulatory system, parameters of which can be adapted to the characteristics of individual patients. The latter tool allows the patient to predict his response to any modification in the therapeutic regime and to learn how variations in timing, formulation and doses of insulin, in carbohydrate equivalents and absorption characteristics of meals, and in exercise may influence the daily pattern in glycaemia. This procedure has been well accepted as an educational tool by those patients who were 'self-managing' their metabolic control.