Diabetic nephropathy--what have we learned in the last three decades?

The past three decades have seen enormous conceptual advances in understanding the pathogenesis of diabetic nephropathy. Increasing evidence points to important genetic determination of the renal risk, i.e. the propensity to develop diabetic nephropathy, in type 1 and type 2 diabetic patients. We are also further along the path to understanding the abnormalities of renal hemodynamics that underly these patients' propensity to develop diabetic glomerulosclerosis, i.e. afferent arterial vasodilation and increased glomerular pressure, identified in elegant experimental studies. Another important advance is the recognition that increased urinary albumin excretion is not only an extremely sensitive marker, but also an important player in the pathogenesis of diabetic nephropathy. Finally, the concept of the toxicity of hyperglycemia ("glucotoxicity") has been carried to the molecular level, so that pathomechanisms such as activation of protein kinase C and cellular damage by advanced glycation endproducts (AGE), to name only two, have been elucidated. Diabetic nephropathy has become the leading cause of endstage renal failure (ESRF) in Western countries, particularly in patients with type 2 diabetes. Three treatment modalities are available: (i) hemodialysis,(ii) CAPD and (iii) transplantation, meaning kidney transplantation, combined pancreas and kidney transplantation or - still in a very preliminary stage - islet cell transplantation. The ideal is to have all three modalities available to meet each patient's individual needs. Treatment outcome continues to be considerably worse, however, in diabetic than non-diabetic patients. This highlights the importance of prevention. Progression to ESRF in diabetic nephropathy is preventable, at least to a large extent.