Should BP targets be lower in diabetic patients with microalbuminuria or nephropathy? A systematic review of randomised controlled trials

Abstract

Does antihypertensive treatment in normotensive patients with diabetic nephropathy alter the progression of kidney failure? We have evaluated studies of renal function which either assessed the effects of different therapeutic blood pressure (BP) goals, or the effects of antihypertensive therapy within the normotensive BP range. Need for renal replacement therapy was regarded as the most valid end point for assessment of deterioration of nephropathy, and change in the glomerular filtration rate (GFR) was regarded as a valid surrogate parameter. Five randomised controlled trials (RCTs) which included normotensive and hypertensive type 1 and type 2 diabetic patients have investigated the effect of lowering of BP within the normotensive range, or from hypertensive values to within the normotensive range. Albumin excretion in urine decreased in the groups randomised to lower BP values, but none of the trials demonstrated any beneficial effect of this intervention on the progression of kidney failure as assessed by the course of GFR. In conclusion, in diabetic patients with microalbuminuria or overt nephropathy, there is no evidence in the literature from RCTs for a beneficial effect of lowering BP within the normotensive range on the risk of kidney replacement therapy or on the loss of glomerular function.