[Diabetes mellitus and osteoporosis. The regulation of glucose metabolism by bone].

Osteocalcin, which is secreted from bone tissue into the circulation, has a hormonal function in glucose metabolism. Previous in vitro and in vivo studies showed that undercarboxylated osteocalcin, but not carboxylated, regulated glucose metabolism by increasing the expression of insulin in pancreatic β cells and adiponectin in adipocytes. Moreover, accumulating clinical studies also indicate that serum osteocalcin level is associated with blood glucose level, parameters of insulin secretion and sensitivity, as well as fat mass. However, it is still unclear whether undercarboxylated osteocalcin is the only one to have the hormonal function in human, or whether interventions for osteoporosis affect glucose metabolism. Therefore, further studies are necessary to clarify these issues.