Diabetic renal disease in type 1 diabetes: aetiology and prevention

Diabetic renal disease affects a subset of about 35% of patients with Type 1 diabetes and is characterized by a triad comprising increased albuminuria, arterial pressure, and volume fraction of the mesangium. This leads to a decline in the glomerular filtration rate and ultimately end-stage renal failure or premature cardiovascular mortality. Individuals at risk can be detected before the development of persistent proteinuria by screening for microalbuminuria which has proved predictive of clinical nephropathy in about 80% of cases. Microalbuminuria is often accompanied by subclinical increases in arterial blood pressure and plasma lipid levels and is usually not apparent until 5 years after stabilization of newly diagnosed diabetes. This latter finding suggests that microalbuminuria is an indicator of early disease rather than a marker of susceptibility to it. Recent evidence suggests that diabetic renal disease may be linked to a familial, possibly genetically determined, predisposition to arterial hypertension or to some factor closely related to the risk of hypertension. This underlying predisposition may be one of the mechanisms leading to severe glomerular damage and may help to explain why clinical renal disease only occurs in a subset of diabetic patients. A number of therapeutic interventions, ranging from strict blood glucose control to low-protein diet and angiotensin-converting enzyme inhibition are effective in reducing or preventing further increases in microalbuminuria. If current long-term trials confirm that treatment of microalbuminuric diabetic patients prevents the onset of heavier persistent proteinuria secondary prevention of diabetic renal failure may become possible. The current criteria for diagnosis of diabetic nephropathy will then require revision.