The ABCD (Appropriate Blood Pressure Control in Diabetes) trial. Rationale and design of a trial of hypertension control (moderate or intensive) in type II diabetes

Abstract

Objective: The primary objective of the ABCD (Appropriate Blood Pressure Control in Diabetes) Trial is to determine the efficacy of intensive versus moderate antihypertensive control on the outcome of type II diabetic end-organ complications in normotensive and hypertensive populations. The secondary objective is to determine whether any differential effect on end-organ complications exists between an angiotensin converting enzyme inhibitor (enalapril) and a calcium channel blocker (nisoldipine).

Design: The ABCD Trial is a prospective, controlled, randomized, double-blind trial, with a planned follow-up of 5 years.

Setting: All patients are seen at the Colorado Prevention Center, site of the ABCD Trial, for follow-up visits.

Patients: Patients are type II diabetic males and females between the ages of 40 and 74 years with entry diastolic blood pressures > or = 80 mmHg. Patients were recruited from University of Colorado-affiliated hospitals, several health maintenance organizations, and mailing lists from the Colorado affiliate of the American Diabetes Association.

Interventions: Patients were randomized to intensive antihypertensive drug therapy or moderate antihypertensive drug therapy. Patients were also randomized to nisoldipine or enalapril, with open-label medications added if further blood pressure control was necessary.

Main outcome measures: The primary outcome measure is glomerular filtration rate as assessed by 24-hour creatinine clearance. Secondary outcome measures are microalbumin urinary excretion, left ventricular hypertrophy, retinopathy, and neuropathy. Cardiovascular morbidity and mortality will also be evaluated.

Conclusion: Given the data showing the impact of hypertension on diabetic complications, the ABCD Trial was designed to determine if intensive antihypertensive therapy will be more efficacious than moderate antihypertensive therapy on the outcome of these complications. Results from the ABCD Trial are expected to lend interpretable and clinically relevant findings with regards to the treatment of hypertension in type II diabetes.