Can Renin-Angiotensin Blockade Prevent Diabetic Retinopathy?
Some evidence suggests that blockade of the renin-angiotensin system can lower the incidence and progression of retinopathy in patients with type 1 diabetes. With manufacturer support, investigators enrolled 3810 adults with nonproliferative diabetic retinopathy (half with type 1 and half with type 2 diabetes) and 1421 adults with type 1 diabetes and no retinopathy in three concurrent trials. Patients were randomized to daily candesartan (Atacand; 32 mg) or placebo and followed for about 5 years. Periodic retinal photographs were graded on a standard 11-step retinopathy scale. Among patients with type 2 diabetes, progression of retinopathy by at least three steps was nonsignificantly less common in the candesartan group than in the placebo group (17% and 19%; P=0.2). Significantly more candesartan patients exhibited regression of retinopathy by at least three steps (a secondary endpoint; 19% vs. 14%; P=0.009). Among patients with type 1 diabetes, incidence of new retinopathy (at least