For the purpose of establishing a specific information system in order to identify the diabetic patients looked after in the hospital and evaluate the processes and the clinical outcomes obtained, a prospective descriptive study was designed--in the Corporació Parc Taulí of Sabadell (Barcelona)--about the diabetic patients cared starting in January 1998, through a clinical registry and other hospital sources of information. Seven hundred and fifty-five patients were identified, and the completeness of the registry was 98%. It was feasible the integration of the registry of admissions with that of the laboratory, that of the discharges from hospital, that of pharmacy and the specific clinical registry. An evaluation of the glycemic control was made in around 90% of the patients, and the registry of the organic explorations was higher than 87%. Although it was not possible in this study, the incorporation of the information from the primary care would complete the follow-up of the patients.