The kidney in type 2 diabetes: focus on renal structure.

The renal lesions underlying renal dysfunction are different in type 2 and type 1 diabetes. Renal structure is heterogeneous in type 2 diabetic patients, with only a subset presenting typical diabetic glomerulopathy, as in type 1 diabetes. The remaining patient have more advanced tubulo-interstitial and vascular than glomerular lesions, or normal/near normal renal structure. The clinical manifestations of diabetic nephropathy are significantly related with glomerular structural changes, especially with the degree of mesangial expansion; however these relationships are less precise than in patients with type 1 diabetes. Probably several other important structural changes are involved, including tubular, interstitial and vascular lesions. Indeed, in the last years, changes in the structure and number of podocytes have been demonstrated to be involved in the pathogenesis of diabetic nephropathy; recently is emerging that also proximal tubular structural abnormalities might contribute to increasing albuminuria in type 2 diabetic patients. This review summarizes the renal structural abnormalities and the structural–functional relationships in type 2, compared to type 1, diabetic patients.