Natural history of diabetic complications: early detection and progression.

Until recently Type 1 diabetes has been characterized by a considerable degree of mortality, mainly associated with the development of diabetic nephropathy. Diabetic nephropathy is characterized by persistent proteinuria, decreasing glomerular filtration rate (GFR), increasing blood pressure, and morphological changes. Proteinuria represents a late stage in a prolonged process, which begins at the onset of Type 1 diabetes, when urinary albumin excretion is at the lower end of its normal range (less than 10 mg 24-h-1). However, in those patients who will later develop persistent proteinuria, urinary albumin excretion increases exponentially at about 20% per year. These patients also tend to have rising blood pressure and falling GFR, higher rates of proliferative retinopathy and coronary heart disease, and elevated levels of cardiovascular risk factors. As intervention is possible in all these areas, identification of such patients is required and especially as the imposition of strict metabolic control may postpone or arrest progression to overt nephropathy. Where patients deteriorate despite such control the institution of early antihypertensive therapy and the effective management of end stage renal disease will bring further improvements in the prognosis of diabetic nephropathy.