The authors have based this critical evaluation on the methods at present adopted for mass screening for symptomatic diabetes in a group of 39,405 subjects, in full working activity. The results obtained from these tests confirm the social importance of this illness in the active population. However, the authors suggest that the glycosuria test be abandoned as the primary discriminating criterium and suggest that blood glucose assay in specimens drawn two hours after a standard glucose and load (50 g as proposed by WHO) and the singling out of potential diabetic individuals by reason of their family and physiological background be adopted for this purpose. The relationship between diabetes, obesity, dysmetabolism and cardiovascular alterations lead us to stress once more the importance of primary prevention, aimed at correcting the eating habits and life style of patients with a potential predisposition to the illness.