Pathogenesis of diabetic nephropathy in non-insulin-dependent diabetes mellitus.

To elucidate the characteristics of diabetic nodular lesions and the process of progression of diabetic glomerulosclerosis, kidney specimens obtained from 185 patients with non-insulin-dependent diabetes mellitus (NIDDM) were observed using light, electron, and immunofluorescence microscopes. The results suggest the following. First, there are two distinct subtypes of nodular lesions: One is formed by the progression and expansion of diffuse lesions; the other, showing a concentrically layered structure, is probably formed in the process of reconstruction of mesangiolysis. Second, there are three phases in the process of progression of diabetic glomerulosclerosis: In the first phase, arteriolosclerosis and diffuse lesions appear; in the second phase, mesangiolysis and nodular lesions develop in association with moderately advanced arteriolosclerosis; and in the third phase, exudative lesions and hyalinized glomeruli appear in association with advanced arteriolosclerosis together with advanced interstitial lesions. In the progression of the phases and in the development of mesangiolysis and layered nodular lesions, disturbed blood flow into glomeruli in consequence of diabetic arteriolosclerosis could be essential.