Ketone body determination is indicated in all diabetic patients when the risk of ketotic decompensation exists. New methods of screening for ketosis, in particular capillary blood ketone body determination, provide analytical, technical and clinical advantages compared to the conventional ketonuria. It is proposed that a diabetic patient with hyperglycaemia (capillary blood glucose > 2.50 g.l(-1)) and capillary blood ketone bodies exceeding 0.5 mmol.l(-1) requires therapeutic management. For values greater than 3 mmol.l(-1) or in case of more serious clinical symptoms, hospitalisation is indicated, considering the high probability of ketoacidotic decompensation. The advantages of capillary blood ketone body determination including easy use, and rapid and objective results may improve management of the diabetic patient, especially in emergency situations. However, prescription by a physician of capillary blood ketone body determination should be offered to targeted populations that have a high risk of ketoacidotic decompensation, after providing education to patients that is above all aimed at preventing this metabolic complication. In this context of determining ketone bodies in capillary blood, the term "capillary blood ketone bodies" is therefore preferable to the term "capillary blood beta-hydroxybutyrate determination". Indeed, it appears more appropriate, simple, descriptive and significant both for health-care staff and for patients.