[Diagnosis, classification and cathogenesis of diabetes mellitus]

Diabetes mellitus (DM) is a metabolic disorder characterized by the presence of chronic hyperglycemia accompanied by greater or lesser impairment in the metabolism of carbohydrates, lipids and proteins. The origin and etiology of DM can vary greatly but always include defects in either insulin secretion or response or in both at some point in the course of disease. When characteristic symptoms of DM are clearly present and blood glucose levels are high enough, the diagnosis is usually unequivocal. However, it is important to remember that the diagnosis is made in asymptomatic patients in most cases, based on the results of routine tests. The prevalence of DM, its specific complications and the presence of other diseases that often accompany DM make this disease one of today's main social and public health problems. The great increase in information available on the etiology and pathophysiology of DM and its chronic complications has led necessarily to the revision of diagnostic criteria and reclassification of the processes involved. Revised diagnostic criteria and classifications were agreed upon in 1997 and 1998 by the American Diabetes Association and the World Health Organization, respectively, and new recommendations were published. Thanks to cross-representation on the committees, the conclusions and final recommendations are, in general, very similar, although a few minor differences are present. Clarification of diagnostic criteria and better classification of patients suffering from DM should allow us to make better choices among the various treatment options available and to improve prognosis.