Sugar and Bone: A Not-So Sweet Story

Abstract

I predict that most readers of the article by Moyer-Mileur and colleagues in this month’s Journal of Bone and Mineral Research will be challenged not just by the results of their study, but also by the long term implications of their findings. In this relatively small, but well done CRU (Clinical Research Unit) investigation, several indices of the growth hormone- IGF-I axis in adolescent girls with at least 5 years of Type I diabetes mellitus (TIDM), were compared to appropriately age and tanner staged- matched controls (1). These parameters were then regressed against measures of skeletal size and content using areal and volumetric bone mass measurements. On first inspection, the results are not surprising, and are consistent with earlier studies from this group and others; i.e. adolescent girls with long standing TIDM have lower serum IGF-I, higher IGFBP-1, and greater growth hormone concentrations than their age-matched controls. Moreover, those girls with poor metabolic control had the lowest circulating IGF-I and highest IGFBP-1 concentrations. In respect to skeletal structure, increased urinary magnesium in the diabetic girls predicted a smaller, lighter skeleton, and overall disease duration accounted for the greatest variability in bone mineral content and cross sectional area. Higher blood glucoses and greater urinary magnesium were also associated with measures of increased bone resorption. Low serum IGF-I was a major predictor of tibial bone strength, as determined by pQCT.