Jessica A Alvarez1, Ambika P Ashraf, Gary R Hunter, Barbara A Gower. 1. Department of Nutrition Sciences and the Department of Pediatrics/Division of Pediatric Endocrinology and Metabolism, The Children's Hospital, University of Alabama at Birmingham, Birmingham, AL, USA. jalvar2@uab.edu
Abstract
BACKGROUND: Circulating 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) concentrations have been shown to be associated with insulin sensitivity; however, adiposity may confound this relation. Furthermore, African Americans (AAs) have lower insulin sensitivity and 25(OH)D concentrations than do European Americans (EAs); whether these differences are associated in a cause-and-effect manner has not been determined. OBJECTIVES: The objectives of this study were to examine the relation of 25(OH)D and PTH concentrations with whole-body insulin sensitivity and to determine whether lower 25(OH)D concentrations in AAs compared with EAs contribute to the lower insulin sensitivity of AAs relative to that of EAs. DESIGN: This was a cross-sectional study of 25 AA and 25 EA women. We determined the whole-body insulin sensitivity index (S(I)) with an intravenous glucose tolerance test and minimal modeling. Percentage body fat was determined with dual-energy X-ray absorptiometry, and intraabdominal adipose tissue (IAAT) was determined with computed tomography. RESULTS: Multiple linear regression analysis indicated that 25(OH)D and PTH concentrations were independent determinants of S(I) [standardized β = 0.24 (P = 0.04) and -0.36 (P = 0.002), respectively] after adjustment for age, race, and IAAT. The mean ethnic difference in S(I) decreased from 2.70 [· 10(-4) · min⁻¹/(μIU/mL)] after adjustment for IAAT and percentage body fat to 1.80 [· 10(-4) · min⁻¹/(μIU/mL)] after further adjustment for 25(OH)D and PTH concentrations. CONCLUSIONS: 25(OH)D and PTH concentrations were independently associated with whole-body insulin sensitivity in a cohort of healthy women, which suggested that these variables may influence insulin sensitivity through independent mechanisms. Furthermore, ethnic differences in 25(OH)D concentrations may contribute to ethnic differences in insulin sensitivity.
BACKGROUND: Circulating 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) concentrations have been shown to be associated with insulin sensitivity; however, adiposity may confound this relation. Furthermore, African Americans (AAs) have lower insulin sensitivity and 25(OH)D concentrations than do European Americans (EAs); whether these differences are associated in a cause-and-effect manner has not been determined. OBJECTIVES: The objectives of this study were to examine the relation of 25(OH)D and PTH concentrations with whole-body insulin sensitivity and to determine whether lower 25(OH)D concentrations in AAs compared with EAs contribute to the lower insulin sensitivity of AAs relative to that of EAs. DESIGN: This was a cross-sectional study of 25 AA and 25 EA women. We determined the whole-body insulin sensitivity index (S(I)) with an intravenous glucose tolerance test and minimal modeling. Percentage body fat was determined with dual-energy X-ray absorptiometry, and intraabdominal adipose tissue (IAAT) was determined with computed tomography. RESULTS: Multiple linear regression analysis indicated that 25(OH)D and PTH concentrations were independent determinants of S(I) [standardized β = 0.24 (P = 0.04) and -0.36 (P = 0.002), respectively] after adjustment for age, race, and IAAT. The mean ethnic difference in S(I) decreased from 2.70 [· 10(-4) · min⁻¹/(μIU/mL)] after adjustment for IAAT and percentage body fat to 1.80 [· 10(-4) · min⁻¹/(μIU/mL)] after further adjustment for 25(OH)D and PTH concentrations. CONCLUSIONS:25(OH)D and PTH concentrations were independently associated with whole-body insulin sensitivity in a cohort of healthy women, which suggested that these variables may influence insulin sensitivity through independent mechanisms. Furthermore, ethnic differences in 25(OH)D concentrations may contribute to ethnic differences in insulin sensitivity.
Authors: Victor Fulgoni; Jill Nicholls; Alan Reed; Rita Buckley; Karen Kafer; Peter Huth; Douglas DiRienzo; Gregory D Miller Journal: J Am Diet Assoc Date: 2007-02
Authors: Shanna Nesby-O'Dell; Kelley S Scanlon; Mary E Cogswell; Cathleen Gillespie; Bruce W Hollis; Anne C Looker; Chris Allen; Cindy Doughertly; Elaine W Gunter; Barbara A Bowman Journal: Am J Clin Nutr Date: 2002-07 Impact factor: 7.045
Authors: Barbara A Gower; Gary R Hunter; Paula C Chandler-Laney; Jessica A Alvarez; Nikki C Bush Journal: Obesity (Silver Spring) Date: 2009-12-24 Impact factor: 5.002
Authors: Claudia Boucher-Berry; Phyllis W Speiser; Dennis E Carey; Steven P Shelov; Siham Accacha; Ilene Fennoy; Robert Rapaport; Yomery Espinal; Michael Rosenbaum Journal: J Bone Miner Res Date: 2012-02 Impact factor: 6.741
Authors: Michelle M Estrella; Gregory D Kirk; Shruti H Mehta; Todd T Brown; Derek M Fine; Mohamed G Atta; Gregory M Lucas Journal: AIDS Date: 2012-01-28 Impact factor: 4.177
Authors: Heather H Burris; Sheryl L Rifas-Shiman; Ken Kleinman; Augusto A Litonjua; Susanna Y Huh; Janet W Rich-Edwards; Carlos A Camargo; Matthew W Gillman Journal: Am J Obstet Gynecol Date: 2012-06-01 Impact factor: 8.661
Authors: Lynae J Hanks; Ambika Ashraf; Jessica A Alvarez; T Mark Beasley; Jose R Fernandez; Krista Casazza Journal: Infant Child Adolesc Nutr Date: 2013-04