[Initial aspects of the changes in diabetic proteinuria].

Proteinuria was analysed quantitatively and qualitatively in 156 diabetics and 63 matched controls. The study was limited to patients with a proteinuria of less than 100 ng/min in the recumbency. The urinary proteins were analysed using cellulose acetate electrophoresis, immunoelectrophoresis and sodium dodecylsulfate poly-acrylamide gel electrophoresis. Abnormal urinary protein patterns were more frequent in diabetics than in the controls (p less than 0.01). However, when the subjects were divided into 2 groups according to their age, the limit being arbitrarily chosen at 60 years, the differences were statistically not significant in the older group. By contrast, in the younger group, the proportion of perfectly normal patterns was significantly decreased in diabetics as compared to the controls (p less than 0.005). In our diabetic population, chosen on the basis of a quantitatively normal proteinuria, no clear relation could be found between the abnormalities of the urinary protein electrophoretic patterns and the patient's clinical data, with the exception of vascular and cardiac complications. Our results suggest that qualitative changes of urinary proteins might be the first signs of renal complications in diabetic patients and that diabetes might constitute an additional cause of aging for the kidneys.