Vascular disease in early stage of diabetic nephropathy

Vascular disease comprising renal microvascular disease and macrovascular disease has been recognized in diabetic nephropathy. The crucial issue remains to be addressed is when it develops during the course of diabetes mellitus. With respect to the renal microvascular disease, its recognition has been well reflected by either histopathologic study of the renal microvessels, or intrarenal hemodynamic study determined by a double isotope techniques namely I-labeled orthoiodohippuric acid to reflect the renal plasma flow, and technitium-labeled diethylene triamine pentaacetic acid to reflect glomerular filtration rate. The intrarenal hemodynamic study in 30 patients associated with early diabetic nephropathy during the stage of normoalbuminuria reveals a significant alteration characterized by reductions in renal plasma flow, peritubular capillary flow as well as an abnormally elevated level of renal arteriolar resistances. It has also been noted that such intrarenal hemodynamic alteration is documented even in the presence of normotension indicating dissociation between systemic and renal microvascular circulations (Table 1). The above findings imply that renal microvascular disease has developed during the early course of diabetic nephropathy. The cause-and-effect relationship between renal microvascular disease and the magnitude of renal functional and structural impairments has been appreciated and thus, signifies the essential role of renal microvascular disease relevant to therapeutic and preventive strategy of the renal disease. With respect to the macrovascular disease in diabetes mellitus, it is a general consensus that the recognition of macrovascular disease is usually precipitated by the onset of major organ damage such as myocardial infarction or cerebrovascular incident. In this regard, many people view that macrovascular disease is associated with late stage diabetes. Surprisingly, the study on macrovascular disease by Cardio-Ankle Vascular Index (CAVI) method in this study revealed that there was an increase in arterial stiffness as well as an advanced estimated age of artery observed in early stage of diabetic patients (normoalbuminuria) as compared to the healthy subjects (Table 1). The presence of both macrovascular disease and renal microvascular disease in normoalbuminuric diabetic nephropathy implies that these two forms of vascular disease develop during the early course of Keywords