[Updates on Lifestyle-Related Diseases and Bone Metabolism. The relationship between incretin and bone metabolism].

There are two kinds of incretin, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) . GIP directly affects osteoblasts and osteoclasts, resulting in increasing bone mass by enhancing bone formation and suppressing bone resorption. On the other hand, GLP-1 does not affect bone directly. GLP-1 is reported to stimulate calcitonin secretion in thyroid gland and then indirectly increase bone mass. Dipeptidyl peptidase-4 inhibitors, which activate the function of incretin, may decrease the risk of osteoporotic fractures. In addition, it has been shown that osteoblast-derived osteocalcin stimulates GLP-1 secretion. Therefore, there may be an interaction between bone and digestive tract.