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Q: What interventions have been proven to delay the progression of diabetic nephropathy?
A: Microalbuminuria, the earliest (and potentially reversible) stage of incipient nephropathy disease, and gross proteinuria precede end-stage renal failure by variable but lengthy intervals. The limited availability of organs for transplantation means that thousands of patients spend several years on dialysis without a chance of receiving kidney transplants. Thus, the emphasis should be on prevention of kidney disease, since cure cannot be offered to all affected persons. The initial observation that microalbuminuria precedes more advanced stages of kidney disease by several years is important. This knowledge creates a window of opportunity to intervene and prevent further decline in renal function. The decline in kidney function can be slowed down considerably if blood pressure is controlled (<130/<80 mm Hg) in persons who have both diabetes and hypertension. It has now been established that angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs)3 are effective in preserving renal function in diabetes patients with microalbuminuria and with more advanced forms of nephropathy. ACE inhibitors are well tolerated by normotensive patients. Thus, the approach to diabetic kidney disease should focus on prevention. In patients with microalbuminuria treated with ACE inhibitors, follow-up urine tests should be obtained and the dose of ACE inhibitor adjusted for maximum nephroprotective effect.2,3,9-11
The combination of an ARB and ACE inhibitor has been suggested as a mechanism to afford optimal cardiovascular and renal protection for patients with type 2 diabetes mellitus and renal disease. This approach is based on the opinion that although ACE inhibitors have demonstrated dramatic reductions in cardiovascular events in clinical trials, they have not been shown convincingly to slow progression of renal disease in patients with type 2 diabetes and macroalbuminuria. Conversely, the ARBs have clearly shown renoprotective effects in this patient population but have not yet been shown convincingly to reduce cardiovascular endpoints.12-14
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