title: Race differences in the association of oxidative stress with insulin sensitivity in African- and European-American women.
abstract: Excessive metabolism of glucose and/or fatty acids may impair insulin signaling by increasing oxidative stress. The objective of this study was to examine the association between insulin sensitivity and protein carbonyls, a systemic marker of oxidative stress, in healthy, nondiabetic women, and to determine if the relationship differed with race. Subjects were 25 African-Americans (AA, BMI 28.4 ± 6.2 kg/m(2), range 18.8-42.6 kg/m(2); age 33.1 ± 13.5 years, range 18-58 years) and 28 European-Americans (EA, BMI 26.2 ± 5.9 kg/m(2), range 18.7-48.4 kg/m(2); age 31.6 ± 12.4 years, range 19-58 years). Insulin sensitivity was determined using an intravenous glucose tolerance test incorporating [6,6-(2)H(2)]-glucose, and a two-compartment mathematical model. Multiple linear regression results indicated that insulin sensitivity was inversely associated with protein carbonyls in AA (standardized regression coefficient -0.47, P < 0.05) but not EA (0.01, P = 0.945), after adjusting for %body fat. In contrast, %body fat was significantly and positively associated with insulin sensitivity in EA (-0.54, P < 0.01) but not AA (-0.24, P = 0.196). Protein carbonyls were associated with free fatty acids (FFA) in AA (r = 0.58, P < 0.01) but not EA (r = -0.11, P = 0.59). When subjects were divided based on median levels of fasting glucose and FFA, those with higher glucose/FFA concentrations had a significantly greater concentration of circulating protein carbonyls compared to those with lower glucose/FFA concentrations (P < 0.05). These results suggest that oxidative stress independently contributes to insulin sensitivity among AA women. Further, this association in AA may be mediated by circulating FFA and/or glucose.
authors.affiliation: Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA. grdnfs@uab.edu
authors.forename: Gordon
authors.initials: G
authors.lastname: Fisher
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Alvarez
authors.forename: Amy C
authors.initials: AC
authors.lastname: Ellis
authors.forename: Wesley M
authors.initials: WM
authors.lastname: Granger
authors.forename: Fernando
authors.initials: F
authors.lastname: Ovalle
authors.forename: Chiara Dalla
authors.initials: CD
authors.lastname: Man
authors.forename: Claudio
authors.initials: C
authors.lastname: Cobelli
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Gower
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007333:Insulin Resistance / Q000208:ethnology / Q000502:physiology*; D008875:Middle Aged; D008962:Models, Theoretical; D018384:Oxidative Stress / Q000502:physiology*; D050050:Protein Carbonylation / Q000502:physiology*; D014481:United States; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified