The effect of high-dose vitamin D3 supplementation on bone mineral density in subjects with prediabetes

Summary The rationale of this study was to determine the effect of high-dose vitamin D3 supplementation on bone mineral density (BMD). Prediabetic males given vitamin D had significantly less reduction in BMD at the femoral neck compared to the controls. The clinical implications of our findings require further investigation. Introduction Type 2 diabetes mellitus is associated with increased fracture risk, and recent studies show crosstalk between bone and glucose metabolism. Few studies have investigated the effect of vitamin D supplementation on the bone without additional calcium. In the present study, we aimed to determine whether a high dose of vitamin D3 could improve bone mass density (BMD) in prediabetic subjects. Methods The current study was conducted as a secondary research on a previously performed trial, in which 511 subjects with prediabetes were randomized to vitamin D3 (20,000 IU per week) versus placebo for 5 years. BMD was measured using dual-energy X-ray absorptiometry (DEXA). Results Two hundred and fifty-six subjects were randomized to vitamin D and 255 to placebo. Mean baseline serum 25-hydroxyvitamin D (25(OH)D) level was 60 nmol/L. Two hundred and two and 214 in the vitamin D and placebo groups, respectively, completed BMD measurements, whereas one in each group was excluded due to use of bisphosphonates. Males given vitamin D had significantly less reduction in BMD at the femoral neck measurement site compared to the controls (0.000 versus − 0.010 g/cm2, p = 0.008). No significant differences between intervention groups were seen at the total hip measurement site, regarding both males and females. Conclusions Vitamin D3 supplementation alone may be beneficial in males with prediabetes, but confirmatory studies are needed