['Type 2 diabetes mellitus (T2DM) with microalbuminuria (MA) is associated with increased risk of cardiovascular events (CVE) that may be attenuated by angiotensin-converting enzyme inhibitors (ACEIs), unless microalbuminuria persists (PMA). African-Americans (AA) have a higher prevalence of nephropathy with suboptimal response to ACEIs. We studied the effects of beta-blockers addition and comparative effects of carvedilol with metoprolol on 24-h urinary-albumin excretion (UAE) and endothelial function (EF) in AA with PMA.', 'Thirty-four AA 30-70 years of age with T2DM and PMA despite ACEI therapy were randomized to receive carvedilol or metoprolol in addition to ACEI and any other concurrent therapy. Carvedilol/metoprolol dose was titrated to achieve blood pressure (BP) <130/80 mm Hg. UAE and brachial-artery reactivity were studied at baseline and 12 weeks. We analyzed the effects of addition of beta-blockers and whether there was any difference in response between the two beta-blockers.', 'Thirty-three subjects completed the study; BP decreased to <135/80 mm Hg. After 12 weeks, beta-blocker treatment resulted in significant increase in flow-mediated dilatation (FMD) from 3.5+/-1% to 8.5+/-1% (P=.004) and significant reduction in mean log-transformed UAE from 2.655 g/g Cr+/-0.087 to 2.533 g/g Cr+/-0.093 (P=.028). FMD increased by 240% (P=.033) with carvedilol and by 110% (P=.096; NS) with metoprolol. UAE decreased with carvedilol by 0.35 g/g Cr (P=.023) and with metoprolol by 0.23 g/g Cr (P=.298; NS).'] Do beta-blockers have a beneficial effect upon endothelial function and microalbuminuria in African-American subjects with diabetes and hypertension?