Vitamin D, Insulin Sensitivity, and Vascular Associations in Adolescents

Overview

The overall objectives of this study are to examine the relationships between circulating vitamin D, insulin sensitivity, and multiple indices of vascular function and to examine whether vitamin D deficiency in AA is responsible for ethnic differences in insulin sensitivity and hypertension in AA and EA, as well as mechanisms underlying the association between insulin resistance and blood pressure. We hypothesize that 1) serum 25(OH)D is associated with insulin sensitivity and vascular functioning, independent of adiposity, 2) lower insulin sensitivity and vascular functioning in AA relative to EA is due to lower circulating 25(OH)D in AA, and 3) the relationship between insulin resistance and vascular dysfunction is mediated by 25(OH)D. Acronyms: African American (AA), European American (EA), Serum 25-hydroxy vitamin D (25()H)D, Body mass index (BMI), Alabama (AL).

Full Title of Study: “Serum 25-hydroxyvitamin D, Vascular Functioning, and Insulin Sensitivity in Adolescent Girls [The DIVA Study (Vitamin D, Insulin, and Vascular Associations)] (Pediatric Physician Training in Translational Research)”

Study Type

  • Study Type: Observational
  • Study Design
    • Time Perspective: Cross-Sectional
  • Study Primary Completion Date: December 2012

Arms, Groups and Cohorts

  • Healthy adolescents
    • Healthy adolescent African American and Caucasian females, ages 14-18

Clinical Trial Outcome Measures

Primary Measures

  • Insulin Sensitivity
    • Time Frame: Cross sectional study: at the first study visit

Secondary Measures

  • Vascular Function
    • Time Frame: Cross sectional study: at the second study visit, within 2 weeks of first study visit

Participating in This Clinical Trial

Inclusion Criteria

  • African American or Caucasian ethnicity – Ages 14-18 yrs – Healthy Exclusion Criteria:

  • BMI-for age and -sex higher than 95th centile on the Centers for Disease Control and Prevention Growth Charts – Use of medication(s) known to influence body composition, vascular function, or glucose metabolism – Pregnancy – Diabetes or any chronic diseases

Gender Eligibility: Female

Minimum Age: 14 Years

Maximum Age: 18 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • University of Alabama at Birmingham
  • Provider of Information About this Clinical Study
    • Principal Investigator: Ambika Ashraf, M.D., Associate Professor, Pediatrics – University of Alabama at Birmingham
  • Overall Official(s)
    • Ambika Ashraf, MD, Principal Investigator, University of Alabama at Birmingham

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