title: Postprandial endothelial function does not differ in women by race: an insulin resistance paradox?
abstract: Insulin resistance is associated with endothelial dysfunction. Because African-American women are more insulin-resistant than white women, it is assumed that African-American women have impaired endothelial function. However, racial differences in postprandial endothelial function have not been examined. In this study, we test the hypothesis that African-American women have impaired postprandial endothelial function compared with white women. Postprandial endothelial function following a breakfast (20% protein, 40% fat, and 40% carbohydrate) was evaluated in 36 (18 African-American women, 18 white women) age- and body mass index (BMI)-matched (age: 37 ± 11 yr; BMI: 30 ± 6 kg/m(2)) women. Endothelial function, defined by percent change in brachial artery flow-mediated dilation (FMD), was measured at 0, 2, 4, and 6 h following a meal. There were no significant differences between the groups in baseline FMD, total body fat, abdominal visceral fat, and fasting levels of glucose, insulin, total cholesterol, low-density lipoprotein cholesterol, or serum estradiol. Although African-American women were less insulin-sensitive [insulin sensitivity index (mean ± SD): 3.6 ± 1.5 vs. 5.2 ± 2.6, P = 0.02], both fasting triglyceride (TG: 56 ± 37 vs. 97 ± 49 mg/dl, P = 0.007) and incremental TG area under the curve (AUC(0-6hr): 279 ± 190 vs. 492 ± 255 mg·dl(-1)·min(-1)·10(-2), P = 0.008) were lower in African-American than white women. Breakfast was associated with a significant increase in FMD in whites and African-Americans, and there was no significant difference in postprandial FMD between the groups (P > 0.1 for group × time interactions). Despite being insulin-resistant, postprandial endothelial function in African-American women was comparable to white women. These results imply that insulin sensitivity may not be an important determinant of racial differences in endothelial function.
authors: Diabetes, Endocrinology, and Obesity Branch, Intramural Program, National Institute of Diabetes and Digestive and Kidney Diseases/NIH, 10 Center Drive, Bethesda, MD 20892-0920, USA. muniyapr@mail.nih.gov
authors: Ranganath
authors: R
authors: Muniyappa
authors: Vandana
authors: V
authors: Sachdev
authors: Stanislav
authors: S
authors: Sidenko
authors: Madia
authors: M
authors: Ricks
authors: Darleen C
authors: DC
authors: Castillo
authors: Amber B
authors: AB
authors: Courville
authors: Anne E
authors: AE
authors: Sumner
mesh_terms: D000328:Adult; D001741:Black or African American; D001786:Blood Glucose; D015992:Body Mass Index; D001916:Brachial Artery / Q000502:physiology; D004730:Endothelium, Vascular / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000208:ethnology* / Q000502:physiology; D008875:Middle Aged; D019518:Postprandial Period / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D014280:Triglycerides / Q000097:blood; D044465:White People
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D014280:Triglycerides