Impaired Endothelial Function in Healthy African-American Adolescents Compared with Caucasians

ObjectiveTo determine whether African-American adolescents have endothelial dysfunction compared with Caucasians and whether differences are a result of differences in insulin sensitivity calculated from total glucose (SI) or secretion.Study designThirty-three Caucasian (13.6 ± 2.6 years of age; body mass index [BMI] 21.6 ± 4.4 kg/m2 mean ± SD) and 25 African-American (13.3 ± 2.9 years of age; BMI 24.0 ± 4.4 kg/m2) adolescents were studied. Forearm blood flow (FBF; plethysmography) was measured before and after 5 minutes of arterial occlusion. SI and acute insulin response to glucose (AIRG) were measured using intravenous glucose tolerance tests and minimal modeling.ResultsBaseline FBF did not differ between races. Postocclusion FBF was lower in African-Americans (17.2 ± 1.2 vs 22.6 ± 1.2 mL/dL/minute, P = .006). AIRG was higher in African-Americans (6050 ± 940 vs 2410 ± 30 μU minute/mL, P = .001). Pubertal stage had no effect. SI did not differ by race or pubertal stage. In African-Americans, percent fall in FVR following arterial occlusion correlated (r = 0.67, P = .001) with log AIRG. No relationships were found between percent fall in FVR and SI in either race.ConclusionAfrican-American adolescents have decreased endothelial function. This may be a result of increased insulin secretion. Endothelial dysfunction in African-American adolescents may predispose to cardiovascular and type II diabetes.