Effect of Blood Pressure Control on Diabetic Microvascular Complications in Patients with Hypertension and Type 2 Diabetes

Objective: The Appropriate Blood Pressure Control in Diabetes (ABCD) Trial is a prospective randomized blinded clinical trial that compares the effects of intensive versus moderate blood pressure control on the incidence and progression of type 2 diabetic complications. The current article discusses the results of 5.3 years of follow-up of 470 patients with hypertension and evaluates the effects of intensive and moderate blood pressure therapy using nisoldipine versus enalapril as the initial antihypertensive medication for nephropathy, retinopathy, and neuropathy.

Research Design And Methods: The 470 hypertensive subjects, defined as having a baseline diastolic blood pressure of > or = 90 mmHg, were randomized to intensive blood pressure control (diastolic blood pressure goal of 75 mmHg) versus moderate blood pressure control (diastolic blood pressure goal of 80-89 mmHg).

Results: The mean blood pressure achieved was 132/78 mmHg in the intensive group and 138/86 mmHg in the moderate control group. During the 5-year follow-up period, no difference was observed between intensive versus moderate blood pressure control and those randomized to nisoldipine versus enalapril with regard to the change in creatinine clearance. After the first year of antihypertensive treatment, creatinine clearance stabilized in both the intensive and moderate blood pressure control groups in those patients with baseline normo- or microalbuminuria. In contrast, patients starting with overt albuminuria demonstrated a steady decline in creatinine clearance of 5-6 ml.min-1.1.73 m-2 per year throughout the follow-up period whether they were on intensive or moderate therapy. There was also no difference between the interventions with regard to individuals progressing from normoalbuminuria to microalbuminuria (25% intensive therapy vs. 18% moderate therapy, P = 0.20) or microalbuminuria to overt albuminuria (16% intensive therapy vs. 23% moderate therapy, P = 0.28). Intensive therapy demonstrated a lower overall incidence of deaths, 5.5 vs. 10.7%, P = 0.037. Over a 5-year follow-up period, there was no difference between the intensive and moderate groups with regard to the progression of diabetic retinopathy and neuropathy. In addition, the use of nisoldipine versus enalapril had no differential effect on diabetic retinopathy and neuropathy.

Conclusions: Blood pressure control of 138/86 or 132/78 mmHg with either nisoldipine or enalapril as the initial antihypertensive medication appeared to stabilize renal function in hypertensive type 2 diabetic patients without overt albuminuria over a 5-year period. The more intensive blood pressure control decreased all-cause mortality.