Ultrastructural characteristics of diabetic nephropathy

Diabetic nephropathy is a major cause of chronic renal failure in Japan, and the prevalence rate has markedly increased during the past decade. Diabetic nephropathy shows various specific histological changes not only in glomeruli but also in the interstitial region. Nodular, diffuse, and exudative lesions, so-called diabetic glomerulosclerosis, are well known as glomerular lesions. At first, they were historically evaluated only by light microscopy, and thus which components of the glomeruli were modified was not sufficiently clear. Subsequent electron microscopic studies clarified that the expansion of the mesangial matrix was the true form of nodular and diffuse lesions, and that insudated serum substance was the real appearance of an exudative lesion. Interstitial lesions also exhibit specific features in diabetic nephropathy. In electron microscopic studies, it was proved that the size of mitochondria and thickness of the tubular basement membrane were increased in diabetic nephropathy. In this review, we introduce typical electron microscopic findings in diabetic nephropathy and recent opinions on the progression of diabetic nephropathy.