Safety of Anti-Diabetic Therapies on Bone

Osteoporosis and diabetic disease have reached epidemic proportion and create significant public health concerns. The prevalence of these diseases is alarming, and indicates that in the US, 50% of elderly individuals are osteoporotic and almost 20% of population has either diabetic or prediabetic conditions (Centers for Disease Control and Prevention; http://www.cdc.gov). Osteoporosis and diabetes share many features including genetic predispositions and molecular mechanisms. The linkage between these two chronic diseases, which stems from overlapping molecular controls involved in bone homeostasis and energy metabolism, creates a possibility that certain anti-diabetic therapies may affect bone. This concurs with recent findings indicating that bone status is closely linked to regulation of energy metabolism and insulin sensitivity. Indeed, bone and energy homeostasis are under the control of the same regulatory factors, including insulin, peroxisome proliferator activated receptor gamma (PPARγ), gastrointestinal hormones such as glucose inhibitory protein (GIP) and glucagon inhibitory peptide (GLP), and bone derived hormone osteocalcin. These factors and related mechanisms control glucose homeostasis and fatty acids metabolism in fat tissue, pancreas and intestine, which are pharmacological targets for anti-diabetic therapies. The same factors contribute to the bone quality by their effect on bone cell differentiation and bone remodeling process. This implies that bone should be considered as a vital target for therapies which modulate energy metabolism. This review is summarizing available data on the skeletal effects of clinically approved anti-diabetic therapies.