Clinical trial NCT01041365: Vitamin D, Insulin Sensitivity, and Vascular Associations in Adolescents
Official title: 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: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Insulin Sensitivity
Flow-mediated Dilation
Arterial Stiffness
Keywords: insulin sensitivity
vascular function
flow-mediated dilation
arterial stiffness
ethnicity
adolescents
females
glucose tolerance
diabetes
hypertension
cardiovascular
Lead sponsor: University of Alabama at Birmingham
Sponsor class: OTHER
First posted: 2009-12-31
Enrollment: 62
Sex: FEMALE
Minimum age (years): 14
Maximum age (years): 18
Standard ages: CHILD
ADULT
Accepts healthy volunteers: yes
Observational model: COHORT
Time perspective: CROSS_SECTIONAL
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Healthy adolescent African American and European American teenagers, ages 14-18, will be recruited form the Birmingham, AL community

Brief summary: 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).


Eligibility criteria: 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

Primary outcomes:
measure: Insulin Sensitivity
timeFrame: Cross sectional study: at the first study visit
Secondary outcomes:
measure: Vascular Function
timeFrame: Cross sectional study: at the second study visit, within 2 weeks of first study visit
Other outcomes:
Locations:
city: Birmingham
country: United States
facility: University of Alabama
state: Alabama
Study officials:
affiliation: University of Alabama at Birmingham
name: Ambika Ashraf, MD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Ashraf AP, Huisingh C, Alvarez JA, Wang X, Gower BA. Insulin resistance indices are inversely associated with vitamin D binding protein concentrations. J Clin Endocrinol Metab. 2014 Jan;99(1):178-83. doi: 10.1210/jc.2013-2452. Epub 2013 Dec 20.
citation: Alvarez JA, Gower BA, Calhoun DA, Judd SE, Dong Y, Dudenbostel T, Scholl J, Ashraf AP. Serum 25-hydroxyvitamin D and Ethnic Differences in Arterial Stiffness and Endothelial Function. J Clin Med Res. 2012 Jun;4(3):197-205. doi: 10.4021/jocmr965w. Epub 2012 May 15.