[Proteinuria in mature diabetic patients. Quantitative and qualitative analysis]

Proteinuria has been analysed in 334 maturity-onset diabetics and 80 matched controls. Proteinuria measured in the recumbent position exceeded 100 mug/min in 53% of the diabetic population. The percentage of excessive proteinuria increased with duration of the disease. Sex and age had no influence. Out of 55 first year diabetics, 49% had abnormal quantitative proteinuria; this is in contrast to 76 longterm diabetics (over 12 years) of whom 38% had proteinuria under 100 mug/min. Electrophoresis and immuno-electrophoresis showed a glomerular pattern in 40%, a tubular pattern in 15% and a mixed pattern in 8% of all the diabetics. 32% of the diabetics with quantitatively normal proteinuria were abnormal qualitatively, and this may be the first manifestation of diabetic nephropathy. Thirty-eight other patients had a normal electrophoretic pattern in spite of increased proteinuria. Proteinuria levels were significantly associated with hematuria, bacteriuria and reduced GFR, but not with leukocyturia, insulin dependence and hypertension. Upright position increased the proteinuria to a greater degree amongst the patients with normal proteinuria. We discuss the role of increased filtration pressure and glomerular permeability in modifying proteinuria in diabetes. Sensitive quantitative and qualitative proteinuria determinations are important tools both in early diagnosis of diabetic nephropathy in clinical practice and in epidemiological studies.