Angiotensin-Converting Enzyme Inhibitors and Progression of Diabetic Nephropathy

A number of studies have examined the effects of angiotensin-converting enzyme (ACE) inhibitors on progression of diabetic renal disease and microalbuminuria in both normotensive and hypertensive patients with Type I diabetes. Four moderately sized, prospective trials in normotensive patients with Type I diabetes, however, clearly show that ACE inhibitors reduce microalbuminuria and preserve renal function without reducing arterial pressure. These studies also show that reductions in microalbuminuria correlate with preservation of renal function. The current study by Ravid and colleagues, in this issue of Annals, is the first to show that ACE inhibitors reduce microalbuminuria and slow progression of renal disease in normotensive patients with Type II diabetes.

Diabetic nephropathy, characterized by increasing levels of microalbuminuria, hypertension, and ultimately renal failure, afflicts approximately 35% to 40% of patients with either type I or type II diabetes [1]. Many studies show the benefits of adequate blood pressure control to slow progression of diabetic renal disease and reduce albuminuria in hypertensive patients with either type I or type II diabetes [2-4]. Moreover, early clinical studies show that any pharmacologic agent that controls arterial pressure slows progression of diabetic renal disease [2, 4]. Recent studies, however, show that angiotensin-converting enzyme (ACE) inhibitors may have selective renal effects that are separate from reduction of arterial pressure [2, 5].

Given these renal effects of ACE inhibitors in established diabetic nephropathy, two important questions remain unanswered: Can we predict development of diabetic nephropathy before the onset of hypertension, that is, what are the risk …