[Biomechanics of bone in experimental diabetic rats]

The biomechanics of bone in diabetics and its response to insulin treatment was not clear. We investigated the impact of alloxan-induced diabetes and insulin treatment on the biomechanical characteristics of bones. Sprague-Dawley rats were divided into three groups: normal control (NC), diabetics (DM), and diabetics treated with insulin (DI). After 3 months the rats were killed. The load at bending test of the femurs was significantly decreased in DM compared to NC and DI. There was no statistical difference between DI and NC. Structurally, DM was significantly lower than NC and DI in the stress at the proportional limit and the maximum load of vertebrae. In material properties, marked deteriorations in the vertebrae were observed in DM and DI. The plasticity of the vertebrae observed in NC disappeared in DM, in which fragility was obvious. DI was not different from DM. We found that the structure and the material property of the bones deteriorate significantly in diabetes induced by alloxan. Insulin treatment inhibits most of biomechanical changes in bone induced by experimental diabetes, but not all of them. The data suggests that the relations between insulin and the material properties of diabetic bones remain to be studied.