The association between insulin levels and cortical bone: findings from a cross sectional analysis of pQCT parameters in adolescents

Recent studies suggest that patients with type 2 diabetes mellitus are at increased risk of fracture, possibly because hyperinsulinaemia is a risk factor for low bone mineral density, which may in turn be a consequence of a lipotoxic effect of visceral and/or intra-muscular fat on bone. In the present study, we investigated whether insulin plays a role in cortical bone development, by performing a cross sectional study based on the Avon Longitudinal Study of Parents and Children, where we examined associations between fasting insulin levels and peripheral quantitative computed tomography (pQCT) parameters as assessed at the mid-tibia, in 2784 boys and girls mean age 15.5 years. In particular, we wished to examine whether associations which we observed were independent of body composition, including intramuscular fat. We found that insulin was inversely related to cortical bone mineral density (BMD(C) ) after adjustment for age, and following further adjustment for height, muscle cross sectional area (MCSA), subcutaneous fat (SAT) and muscle density (MD) (inversely related to intramuscular fat) [-0.018 (95%CI:-0.030,-0.006), P