[Osmoregulatory function of the kidneys in diabetes mellitus]

In 42 patients with insulin dependent diabetes mellitus of average and grave forms with preserved glomerular renal function without signs of dehydration and hypovolemia renal function was investigated by maximum osmotic urine concentration (on dry food for 36 h) which was assessed on the basis of maximum osmolarity of urine and renal capacity for osmotic dilution of urine (on the 2nd hour after water load per os, 20 ml per 1 kg of body mass) assessed on the basis of the clearance of osmotically free water from 100 ml of the glomerular filtrate. Disorder of function of osmotic urine concentration revealed in 1/4 th of the patients, was moderate; it was most frequent in complication of disease with diabetic glomerulosclerosis, less frequent in diabetic angiopathies and was absent in patients without vascular lesion. Disorder of the capacity of the kidneys for osmotic urine dilution was revealed in 50% of the patients, it was probably of functional nature and was mainly associated with raised permeability of nephron distal segments for water.