Diabetic renal disease: microalbuminuria, implications and intervention.

Diabetic nephropathy is the leading cause of end-stage renal failure in the developed world. Proteinuria ("macroalbuminuria" > 200 micrograms/min; or 300 mg/24 h) heralds a phase of established renal pathology with inexorable decline to end-stage renal disease, although its progression can be delayed by antihypertensive medication, in particular the angiotensin-converting enzyme inhibitors (ACEI). Control of blood pressure is vital; even if in the normal range, it is usually raised compared with that in nondiabetic control groups. Reducing blood pressure can lower the rate of decline of the glomerular filtration rate by 90%. Before established proteinuria there is a "microalbuminuric" (20-20 micrograms/min, or 30-300 mg/24 h) phase, and during this time preventive intervention may be effective. In so-called "normotensive" microalbuminuric subjects antihypertensive medications, in particular the ACEI, significantly reduce the progression to macroalbuminuria. Control of glycemia is important; recent evidence has shown that it is particularly important before the development of microalbuminuria; thereafter the role of glycemic control is not clear. Some researchers have suggested that protein restriction may be helpful, but more data are required. For the moment, improved glycemic control in the normoalbuminuric diabetic subjects and treatment with ACEI after the onset of microalbuminuria would seem appropriate in light of knowledge today. Furthermore, any level of hypertension is totally unacceptable and should be treated aggressively; the ACEI seem to be becoming the "agents of choice."