title: Higher Serum Insulin Concentrations Positively Influence the Bone Mineral Density in African American Adolescents.
abstract: BACKGROUND
  Puberty is a developmental stage of increased insulin resistance that also is a critical period for bone mass accrual. Historically, African Americans (AA) have lesser risk for osteoporotic fractures compared to European Americans (EA). AA also have higher incidence of insulin resistance. The possibility that bone health and insulin secretion or concentrations are linked has not been investigated.
  
  
  OBJECTIVE
  We aimed to examine the associations of bone mineral density (BMD) and bone mineral apparent density (BMAD) with insulin sensitivity and secretion in healthy adolescent girls and healthy female adults and to evaluate ethnic differences in these associations.
  
  
  METHODS
  Observational cohort design.
  University of Alabama at Birmingham, between January 2010 and September 2011.
  
  
  METHODS
  Healthy, female, non-smoking adolescents and young adults (14-55 years) were enrolled in this observational cohort study.
  
  
  RESULTS
  Adolescents had significantly higher fasting insulin (P=0.0002), insulin area under the curve [AUC] (P= 0.0004) and lower insulin sensitivity (P=0.0005) compared to adults. Among adolescents, AA race was significantly associated with BMD (β=0.086, P=0.01) and BMAD (β=0.0075, P=0.002); however, adjusting for insulin AUC explained this difference. Insulin AUC (β=0.0006, P=0.029) and fasting insulin (β=0.0005, P=0.01) were positively associated with BMAD only in AA adolescents. Insulin AUC and fasting insulin were not significant predictors of BMD for adults.
  
  
  CONCLUSIONS
  The higher insulin concentration among AA adolescents is associated with increased BMD and higher BMAD.
authors.affiliation: Department of Pediatrics/Division of Pediatric Endocrinology and Metabolism, The Children's Hospital, University of Alabama Birmingham, Birmingham, USA.
authors.forename: Ambika P
authors.initials: AP
authors.lastname: Ashraf
authors.affiliation: Division of Endocrinology, Emory University School of Medicine, Atlanta, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Alvarez
authors.affiliation: Center for Clinical and Translational Sciences, University of Alabama at Birmingham, USA.
authors.forename: Carrie
authors.initials: C
authors.lastname: Huisingh
authors.affiliation: Department of Nutrition Sciences, University of Alabama Birmingham, Birmingham, USA.
authors.forename: Krista
authors.initials: K
authors.lastname: Casazza
authors.affiliation: Department of Nutrition Sciences, University of Alabama Birmingham, Birmingham, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Gower
keywords: Bone mineral density; bone mass; ethnic differences; insulin secretion