The hypertensive and normotensive Appropriate Blood Pressure Control in Diabetes (ABCD) studies were prospective, randomized, interventional clinical trials with 5 years of follow-up that examined the role of intensive versus standard blood pressure control in a total of 950 patients with type 2 diabetes mellitus. In the hypertensive ABCD study, a significant decrease in mortality was detected in the intensive blood pressure control group when compared with the standard blood pressure control group. There was also a marked reduction in the incidence of myocardial infarction when patients were randomly assigned to initial antihypertensive therapy with angiotensin-converting-enzyme inhibition rather than calcium channel blockade. The results of the normotensive ABCD study included associations between intensive blood pressure control and significant slowing of the progression of nephropathy (as assessed by urinary albumin excretion) and retinopathy, and fewer strokes. In both the hypertensive and normotensive studies, mean renal function (as assessed by 24 h creatinine clearance) remained stable during 5 years of either intensive or standard blood pressure intervention in patients with normoalbuminuria (<30 mg/24 h) or microalbuminuria (30-300 mg/24 h) at baseline. By contrast, the rate of creatinine clearance in patients with overt diabetic nephropathy (>300 mg/24 h; albuminuria) at baseline decreased by an average of 5 ml/min/year in spite of either intensive or standard blood pressure control. Analysis of the results of 5 years of follow-up revealed a highly significant correlation of all-cause and cardiovascular mortality with left ventricular mass and severity of albuminuria.