Relationship between osteocalcin and glucose metabolism in postmenopausal women

BACKGROUND: Recently, osteocalcin was found to regulate blood glucose, insulin secretion, and fat deposition in mice. However, the relationship between osteocalcin levels and factors related to glucose metabolism in humans has not yet been investigated. We investigated the relationship between osteocalcin and glucose metabolism in postmenopausal women. METHODS: Three hundred thirty-nine postmenopausal women were recruited for this study. Glucose metabolism related substance and serum osteocalcin were assayed. RESULTS: There was a significant reduction in osteocalcin levels among type 2 diabetes mellitus patients compared with the normal glucose and impaired fasting glucose groups. Next, the subjects in the highest quartile for osteocalcin were observed to have significantly decreased fasting glucose and HbA1c levels compared with subjects in the lowest quartile. In addition, osteocalcin levels were inversely correlated with glucose, insulin, HbA1c, and insulin resistance. Moreover, multivariate analysis showed that serum osteocalcin was found to be an independent factor associated with glucose and HbA1c. CONCLUSIONS: There is a potential role of osteocalcin in regulating blood glucose levels in postmenopausal women. This finding indicates that in humans the skeleton may be involved in energy metabolism by functioning as part of the endocrine system.