Higher Serum Insulin Concentrations Positively Influence the Bone Mineral Density in African American Adolescents

Abstract

BackgroundPuberty 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.AimsWe 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.Study DesignObservational cohort design.Place and Duration of the StudyUniversity of Alabama at Birmingham, between January 2010 and September 2011.MethodologyHealthy, female, non-smoking adolescents and young adults (14–55 years) were enrolled in this observational cohort study.ResultsAdolescents 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.ConclusionThe higher insulin concentration among AA adolescents is associated with increased BMD and higher BMAD.

Dietary restrictions, bone density, and bone quality

“…At the cellular level, osteoblasts express insulin receptors and are the targets of insulin, which have been confirmed to stimulate osteoblastogenesis in vivo and in vitro . The serum levels of insulin have also been reported to positively correlate with the development of body size, body fat, and bone mass throughout populations of children, adolescents, and adults . Hence, it is understandable that the lower insulin levels that are associated with dietary restriction may cause lower bone mineral accumulation.…”

“…103 The serum levels of insulin have also been reported to positively correlate with the development of body size, body fat, and bone mass throughout populations of children, adolescents, and adults. [104][105][106][107] Hence, it is understandable that the lower insulin levels that are associated with dietary restriction may cause lower bone mineral accumulation. Although lower anabolism and lower bone mass related to dietary restriction have long been considered detrimental to bone health, it is those anabolic and growth/development-related hormones that accelerate the process of aging and tend to impair bone quality.…”