Researchers from the Wake Forest University School of Medicine and the University of East Anglia have found that a long-term use of a popular class of oral diabetic drugs doubled the risk of fractures in women with type 2 diabetes.

Although it was previously known that there is an association between thiazolidinediones and fracture risk, the magnitude of the risk had not been evaluated. The new study shows that these agents double the risk of fractures in women with type 2 diabetes, who were already at higher risk even before taking the therapy.

Statistically, if thiazolidinediones (TZDs) were used by elderly, postmenopausal women (around 70 years) with type 2 diabetes for one year, there would be an additional fracture among every 21 women. In younger women (around 56 years), the use of these drugs for one year or longer would result in an additional fracture in every 55th woman.

Currently, there are two available drugs in this class: rosiglitazone, marketed as AvandiaTM by GlaxoSmithKline, and pioglitazone, marketed as ActosTM by Takeda Pharmaceuticals. These are oral medications that lower blood sugar and in that way control diabetes.

The study that looked at nearly 14,000 cases of impaired glucose tolerance and type 2 diabetes and the effects of TZD therapy on them found that the use of TZDs significantly increased the risk of fractures among the patients with type 2 diabetes and was also associated with changes in bone mineral density at the lumbar spine and the hip.

Sex-specific studies showed that TZDs significantly increased the risk of fractures among women and a consistent decline in bone mineral density.

Other recent studies of TZDs focused on the adverse effects of rosiglitazone and pioglitazone on cardiovascular health of the patients taking them.

Back in 2007, researchers found that TZDs doubled the risk of congestive heart failure in patients with type 2 diabetes. They also found that the use of rosiglitazone was associated both with increased heart attacks and a doubling of heart failure. The researchers reported that for the time being, there is almost no justification for the use of thiazolidinediones.