Bone metabolism in type 2 diabetes and role of thiazolidinediones

To assess bone turnover both at the biochemical and organ level in patients with type 2 diabetes (T2D) and the effects of the thiazolidinediones.

Studies have shown a decreased bone formation and an increased risk of fractures in patients with T2D. Changes in bone strength from glycation of collagen and negative calcium balance from calcium loss in the urine due to hyperglycaemia may also be seen. The thiazolidinediones affect bone turnover by increasing the formation of adipocytes instead of the bone-forming osteoblasts from the common mesenchymal stem cell. A decreased bone formation with decreased bone density and an increased risk of fractures has been observed among users of thiazolidinediones. Differences exist between type 1 diabetes (T1D) and T2D with a much higher increase in the risk of hip fractures in T1D than in T2D compared with the general population. The often higher body mass index in T2D than in T1D appears to explain some of the differences in risk of fractures.

Diabetes is a hitherto overlooked risk factor for osteoporosis and fractures. Thiazolidinediones may increase risk of fractures and should not be used by patients at risk of fractures. More research is needed.