OBJECTIVE: to assess the economic and epidemiologic impact of diabetes in Campania a region of approximately 5.7 million inhabitants in the south of Italy. METHOD: we collected, from an electronic database, all prescriptions for antidiabetic drugs reimbursed in the first half year of 2005 in 8 local health authorities (60% of the overall population) of Campania. The diabetic cohort was defined as the population of subjects receiving at least one prescription of an antidiabetic agent, classified according to their therapeutic role using Anatomic Therapeutic Chemical (ATC) classification. We identified 3 groups: who received only insulin (A) or only oral blood glucose lowering drugs (B) or both (C). Drugs cost and drugs consumption were quantified using NHS prospective (expressed in Euro 2005) and Defined Daily Dose system (DDD) respectively. RESULTS: The diabetic cohort included 200070 subjects (5.7% of the observed population): 15.3% group A (mean age 62.7±17.9 y.o., 0.78 M/F), 78.5% group B (mean age 65.7±12.2 y.o., 0.85 M/F) and 6.2% group C (mean age 66.5±11.1 y.o., 0.57 M/F). The mean drug/cost/patient was: 524.6€ group A (36.6% insulin, 27.1% cardiovascular drugs), €290.4 group B (11.1% oral hypoglycemic drugs, 47.1% cardiovascular drugs) and €649.8 group C (25.7% insulin, 5.4% oral hypoglycemic drugs, 34.6% cardiovascular drugs). Total cost for diabetic patients represents 17.8% of the total expenditures. DISCUSSION: Chronic-degenerative pathologies, such as diabetes, implies a relevant social and economic impact. Expenses that are associated to the treatment and the prevention of complications, in particular cardiovascular problems, are registered among the main items listed in the healthcare budget. Among diabetics patients the high use of drugs for cardiovascular problems is the cost driver.