Diabetic nephropathy: Renal structural studies in type 1 and type 2 diabetic patients

The clinical manifestations of diabetic nephropathy, proteinuria, decreasing glomerular filtration rate and increasing blood pressure are similar in type 1 and type 2 diabetes, while the renal lesions differ. Indeed, in type 1 diabetes, although also tubular, interstitial and arteriolar lesions are present, the most important structural changes involve the glomerulus, in contrast several type 2 diabetic patients, despite the presence of microalbuminuria or proteinuria, have normal glomerular structure with or without tubulo-interstitial and arteriolar abnormalities. The renal functional parameters are strongly related with the structural changes, especially with the degree of mesangial expansion in both type 1 and type 2 diabetes. Previous studies using light and electron microscopic morphometric analyses described the renal structural changes and the structural-functional relationships of diabetic nephropathy. This review focuses on these topics, documenting the contribution of renal biopsy studies in understanding the pathogenesis of diabetic nephropathy and in identifying the patients with higher risk to progress to end-stage renal disease. (C) 2003 Elsevier Science B.V. All rights reserved.