Effects of teriparatide and low-intensity aerobic exercise on osteopenia in type 2 diabetes mellitus rats

Introduction In patients with type 2 diabetes mellitus (T2DM), bone fragility increases fracture risk. Teriparatide (TPTD) improves bone strength, and exercise therapy suppresses blood glucose levels in T2DM. In this study, the combined effects of TPTD and exercise therapy on trabecular and cortical bone were examined in advanced T2DM model rats. Materials and methods Thirty-week-old Otsuka Long–Evans Tokushima Fatty rats were divided into four groups ( n = 9–10 in each group at two time points): Cont group (vehicle-treated control), TPTD group (TPTD 30 μg/kg injected subcutaneously, 3 times/week), Exe group (treadmill exercise, 10 m/min, 60 min/day, 5 times/week), and Comb group (TPTD-treated and treadmill exercise combined). Five and 10 weeks after treatment, bone mineral density (BMD), bone strength, and bone micro-architecture were measured. Results TPTD and combined treatment significantly increased BMDs of the lumbar spine and femur compared to the Cont group ( p < 0.05 to p < 0.01). In the three-point bending test of the femur, only combined treatment increased the maximum load at 5 weeks compared with the Cont and Exe groups ( p < 0.01). In the compression test of the distal femoral metaphysis, both TPTD and combined treatment increased the trabecular bone strength compared with the Cont and Exe groups ( p < 0.05 to p < 0.01). Although TPTD and combined treatment improved the micro-architecture of trabecular bone ( p < 0.05 to p < 0.01), only combined treatment improved the micro-structures of cortical bone from 5 weeks of treatment ( p < 0.05 to p < 0.01). Conclusion The combination of TPTD and treadmill exercise increased BMD and trabecular and cortical bone strength of the femur with improved micro-architecture in T2DM model rats.