GLP1R and diabetes mellitus: The anabolic and antiresorptive effects of GLP-1 receptor suggest that GLP-1 receptor signaling may be a promising therapeutic target for osteoporosis or other osteolytic bone diseases; such a therapeutic approach would be facilitated by the fact that the first commercially available GLP-1 receptor agonist, exendin-4, has already been approved for the treatment of diabetes for over 10 years [38].