Thiazolidinediones and bone.

Diabetes mellitus and osteoporosis are two frequent multifactorial medical conditions with an increasing prevalence in the aging population. Patients with type 2 diabetes mellitus have an increased fracture risk despite a higher bone mineral density (BMD), which is mainly due to the increased risk of falls. Adequate glycemic control and prevention of diabetic complications are also the mainstay of therapy in type 2 diabetes mellitus. The thiazolidinediones (TZDs) have been demonstrated to improve insulin sensitivity and currently represent a widely prescribed treatment for type 2 diabetes. Their action is mediated by the binding to the nuclear receptor and transcription factor, peroxisome proliferator-activated receptor- γ (PPAR- γ), regulating the activity of other transcription factors in the adipogenic differentiation and inflammatory response pathways. The activation of PPAR- γ by TZDs may also cause an increase in bone marrow adiposity and a decrease in osteoblastogenesis, resulting in reduced bone formation. Clinical data are pointing out that the intake of thiazolidinediones by older patients with type 2 diabetes correlates with both the decrease of bone mineral density in the femoral neck and hip and a higher risk for fractures. Thus, health care providers, not only physicians, should carefully check the existence of risk factors for osteoporosis and factures in their patients before selecting them for thiazolidinediones treatment. Moreover, an adequate clinical follow-up of treated subjects is strongly recommended.