HISTOPATHOLOGICAL AND FUNCTIONAL-STUDY OF THE KIDNEY IN NON-INSULIN-DEPENDENT DIABETES

The histopathological characteristics of the kidney using light micros copy and immunofluorescence studies in samples obtained by renal percu taneous biopsy in 19 women and 7 men with non-insulin dependent diabet es mellitus (NIDDM) (mean of age: 55.07 +/- 9.04 yr and mean of ''know n'' diabetes duration: 7.50 +/- 6.87 yr) were studied. The relationshi p with age, blood pressure, diabetic retinopathy and other complementa ry diagnostic methods such as serum creatinine (Cr), creatinine cleara nce (CrC), renal plasma flow (RPF), proteinuria and filtration fractio n (FF) were also determined. Light microscopy studies detected 92.3% o f patients with renal lesions of different degrees of severity. The pr esence and severity of glomerulopathy and arteriolopathy were related to diabetes duration (r: 0.764) and they were related to each other (r s: 0.773). In 2 patients, lesions were not observed and in 11 out of 1 4 patients with less than 5 yr of diabetes duration, mild lesions were detected. However, the histological changes became worse after that p eriod. The glomerulopathy was also statistically correlated with Cr, C rC, RPF, proteinuria and FF. By immunofluorescence, fibrinogen, IgA an d C3 were the more frequent and intense precipitates observed. They in creased with diabetes duration and were located predominantly in the w all and the periphery of the glomerules and in renal tubules, suggesti ng that they originated by trapping. There were no precipitates in the mesenchyma, they were scarce in the interstice, Bowman's capsule and arterioles. Statistical correlation between diabetic histopathological renal changes and retinopathy was found. These results confirm that l esions in the kidney and retina in non-insulin dependent diabetic pati ents generally appear and evolve in a similar manner. Hypertension was diagnosed in 80.76% of patients, without statistical correlation betw een blood pressure and renal lesions. This suggests that at the onset, in non-insulin dependent diabetic patients hypertension and nephro-pa thy are caused by different and independent pathogenic mechanisms. How ever, at an end stage, it seems that both situations can influence eac h other in a way that their evolution becomes more severe. Nephropathy in non-insulin dependent diabetes mellitus displayed scarce clinical signs and poor laboratory evidence except when the renal lesions becom e too severe. The lack of correlation between renal lesions and patien ts' age and blood pressure suggests the participation of diabetes at t he onset of kidney structural impairment.