Diseases of Renal Microcirculation: Diabetic Nephropathy

The prevalence of diabetes mellitus and its long-term vascular complications are increasing worldwide. Diabetic nephropathy is one of the main microvascular complications of diabetes and is characterized by the development of persistent macroalbuminuria (i.e., a urinary albumin excretion [UAE] >300 mg/24 h) or proteinuria (i.e., a urinary protein excretion >0.5 g/24 h). Characteristic glomerular changes of diabetic nephropathy include thickening of the glomerular basement membrane (GBM), mesangial expansion, and podocyte injury. Since type 1 and type 2 diabetic nephropathies share similar histologic characteristics as well as structural-functional relationships, one common classification is used to describe the pathologic classification of diabetic nephropathy for both type 1 and 2 diabetes. Although UAE should rather be considered as a continuous variable rather than using specific cutoff values, we describe the clinical course of diabetic nephropathy based on the classic approach using three stages based on urinary albumin excretion (i.e., normoalbuminuria, microalbuminuria, and macroalbuminuria). Diabetic nephropathy is a major independent risk factor for diabetes-related morbidity and mortality. However, a number of interventions are available that can reduce the risk of developing diabetic nephropathy and slow the progression hereof. Key treatment strategies that could reduce the incidence and progression of diabetic nephropathy include blood glucose control, blood pressure control, lipid-lowering therapy, and lifestyle interventions.