Deterioration of Bone Quality by Streptozotocin (STZ)-Induced Type 2 Diabetes Mellitus in Rats

Patients with diabetes mellitus (DM) have various skeletal disorders and bone quality can be impaired in DM leading to fractures. Wistar albino male rats (270-300 g; n=16) were assigned randomly to nondiabetic and diabetic rats (single dose intravenous injection of 45 mg/kg streptozotocin). All rats in each group were perpetuated for 8 weeks, and blood glucose levels as well as body weights were measured once weekly. Biomechanical measurements were performed at the mid-diaphysis of the left femur with tensile test. Extrinsic and intrinsic properties were measured or calculated. Bone mineral density (BMD) was also evaluated and measured by dual-energy X-ray absorptiometry. Cross-sectional area of the femoral shaft was evaluated by computerized tomography. Blood glucose levels in diabetic rats were significantly increased compared to that of the nondiabetic rats, while the body and femur weights were decreased (P<0.05). In respect to the BMD, cross-sectional area and femur length, there were no statistically significant differences between the nondiabetic and diabetic rats (P>0.05). The maximum load, ultimate stress, and toughness endpoints in diabetic rats were significantly decreased compared to that of the nondiabetics (P<0.05). There were no statistically significant differences between the nondiabetic and diabetic rats with regard to the displacement and stiffness (P>0.05). Femurs of diabetic rats had less absorbed energy than that in nondiabetics (P<0.05). Ultimate strain was lower in diabetic rats than that in nondiabetics, while the elastic modulus was higher (P>0.05). The bone quality of rats is decreased by streptozotocin-induced type 2 diabetes mellitus.