[The functional kidney reserves of diabetics]

Ten patients with insulin-dependent diabetes mellitus not associated with any signs of diabetic nephropathy were examined for the reserves of filtration renal function and early morphological alterations in organ tissues. The reserves of filtration were detected under the conditions of acute oral administration of protein (1.5 g/kg) as difference between the initial and stimulated levels of glomerular filtration (GF). Two groups of patients were distinguished: group I included patients with preserved filtration reserves (increment of GF amounted to 35%), group II included patients with no filtration reserves (reduction of GF was 20%). Both the groups differed significantly only in the initial level of GF (120 and 209 ml/min, respectively) and in the degree of morphological changes in the glomeruli: group I manifested minimum structural changes, group II showed the commencing diabetic glomerulosclerosis characterized by pronounced injury to the manubrium of the glomeruli. Therefore, the lack of filtration reserves in diabetes mellitus patients suggests the presence of the commencing diabetic glomerulonephritis even with the lack of the clinical signs of renal injury, which does not require the resorting to organ biopsy. The primary injury to the manubrium of the glomeruli is likely to be related to a high gradient of intraglomerular hydrostatic pressure, resulting in hyperfiltration.