Diabetic nephropathy: clinical and histological study in 22 patients.

Twenty-two patients with insulin-dependent diabetes mellitus and renal involvement were submitted to renal biopsy. Mean age was 42 years; 10 were males, 12 females. The mean interval between clinical manifestation of nephropathy and biopsy was about 2 years. At the time of biopsy, 4 groups were distinguished according to clinical conditions, depending on the presence or absence of nephrotic syndrome and renal failure. Renal lesions were semiquantitatively evaluated, a separate score being considered for glomerular and vascular lesions. Immunofluorescence most frequently showed a pattern of faint linear IgG deposits along glomerular basement membranes. Severity of histological lesions and pattern of urinary abnormalities were not correlated with the duration of diabetes or the patients' age. Both glomerular and vascular lesions were correlated with the presence of renal failure, while no relationship with the pattern of urinary abnormalities was found. Fourteen patients were followed for more than one year after biopsy: 5 had normal renal function, 4 were in chronic renal insufficiency and 5 in end-stage renal failure (3 were in dialysis, 2 died). There was no correlation between the 3 above-mentioned types of evolution and glomerular histological findings. Nevertheless a higher score of vascular impairment at biopsy was observed among patients who subsequently were found to have a more unfavorable prognosis. Therefore renal biopsy, by providing information on the degree of renal vascular damage, may have some value in predicting the clinical course of diabetic nephropathy.