TUBULOINTERSTITIAL LESIONS IN PATIENTS WITH NON-INSULIN-DEPENDENT DIABETES MELLITUS AND DECLINE IN GLOMERULAR FILTRATION RATE

Abstract

To evaluate the role of tubulointerstitial lesions in diabetic nephropathy, we studied the renal histological findings and various functional parameters in 201 patients with non-insulin-dependent diabetes mellitus (NIDDM). The patients were divided into four groups according to the severity of the tubulointerstitial lesions on a scale of T0 through TⅢ. Diffuse glomerular lesions were graded by Gellman's criteria (D0 through DⅣ). There was a weak correlation between the severity of glomerular diffuse lesions and that of tubulointerstitial lesions ; discordance between glomerular and tubulointerstitial lesions was presest in 37 patients (18%). Urinary excretion of β₂ MG and NAG significantly increased with the severity of tubulointerstitial lesions, whereas the creatinine clearance decreased. Multiple regression analysis showed that glomerular and tubulbinterstitial lesions independently contribute to the decline of the glomerular filtration rate. These results suggest that tubulointerstitial lesions are involved in the progression of diabetic nephropathy.