Role of Blood Pressure Targets and Specific Antihypertensive Agents Used to Prevent Diabetic Nephropathy and Delay Its Progression

This study evaluated the comparative effects of antihypertensive agents in patients with diabetes and normoalbuminuria and the evidence supporting equivalent use of angiotensin-converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARB) in patients with diabetes and micro- or macroalbuminuria. A systematic review was conducted by searching for randomized controlled trials (RCT) of antihypertensive agent versus placebo or another agent in hypertensive or normotensive patients with diabetes and no nephropathy and RCT of ACEi or ARB in patients with diabetic nephropathy. Medline, Embase, the Cochrane Controlled Trials Register, conference proceedings, and contact with investigators were used to identify available evidence. Two investigators independently extracted data and assessed quality of trials. Sixteen RCT (7603 patients) of antihypertensive agents conducted in patients with diabetes and no nephropathy and 43 (7739 patients) of ACEi or ARB in patients with diabetic nephropathy were identified. A significant reduction in the risk for developing microalbuminuria in patients who had diabetes with no nephropathy was demonstrated for ACEi only (six trials, 3840 patients; relative risk [RR] 0.60; 95% confidence interval [CI] 0.43 to 0.84), and in patients with diabetic nephropathy, existing RCT have shown a survival benefit of ACEi (20 trials, 2383 patients; RR 0.79; 95% CI 0.63 to 0.99; P = 0.04) but not ARB (four trials, 3329 patients; RR 0.99; 95% CI 0.85 to 1.17). On the basis of available RCT evidence, ACEi are the only agents with proven renal benefit in patients who have diabetes with no nephropathy and the only agents with proven survival benefit in patients who have diabetes with nephropathy.