Impaired endothelial function in healthy African-American adolescents compared with Caucasians

Objective: To 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 (S,) or secretion. Study design: Thirty-three Caucasian (13.6 +/- 2.6 years of age; body rnass index [BMI] 21.6 +/- 4.4 kg/m(2) mean +/- SD) and 25 African-American (13.3 +/- 2.9 years of age; BMI 24.0 +/- 4.4 kg/m(2)), adolescents were studied. Forearm blood flow (FBF; plethysmography) was measured before and after 5 minutes of arterial occlusion. S, and acute insulin response to glucose (AIRG) were measured using intravenous glucose tolerance tests and minimal modeling. Results: Baseline 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 Atrican-Americans (6050 +/- 940 vs 2410 +/- 30 mu U minute/mL, P = .001). Pubertal stage had no effect. S, 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 S, in either race. Conclusion: African-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 11 diabetes.