Randomised controlled trials (RCTs) that compared the effects of beta-blocker therapy with other antihypertensive therapy on cardiovascular outcomes in hypertensive patients with diabetes mellitus were eligible for inclusion. Trials of primary diabetic cohorts with hypertension and trials of new onset diabetics were excluded. The primary review outcomes were myocardial infarction, stroke, cardiovascular mortality and total mortality. Secondary outcomes were fatal and nonfatal myocardial infarction and fatal and non-fatal stroke.
The included trials compared beta-blockers (atenolol or metoprolol) regimens with calcium channel blockers (amlodipine, diltiazem, felodipine, isradipine, renin angiotensin and verapamil) and renin-angiotensin blockade agents (captopril, enalapril, lisinopril, losartan and perindopril). In some trials, treatment arms classified as beta-blocker based used either beta-blockers or diuretics. All of the trials were in hypertensive patients with diabetes mellitus controlled with insulin, oral agents or a combination of both. Where reported, the mean age of patients ranged from 52 to 76 years. The duration of follow-up ranged from 2.7 to 8.4 years.
Two reviewers independently selected studies and resolved disagreements by discussion.