Potential mechanisms contributing to low bone mass and increased fracture susceptibility in diabetes mellitus.
“Clinical trials have revealed a startling elevation in fracture risk in diabetic patients,” says Liyun Wang, associate professor of mechanical engineering at the University of Delaware. “Bone fractures can be life threatening – nearly one in six hip fracture patients dies within a year of injury.” As physical exercise is proven to improve bone properties and reduce fracture risk in non-diabetic people, Wang’s group decided to test its efficacy in Type 1 diabetes.
Osteocytes are critical to maintenance of the tissue quality and mechanical integrity of bone. As the primary “mechanosensing” cells, osteocytes orchestrate bone’s adaptation processes under mechanical cues such as exercise. “We suspected that the response of diabetic bone to mechanical loading would be compromised due to impaired mechanosensing of osteocytes under hyperglycemic, or high blood sugar, conditions,” she says.
The study demonstrated that exercise-induced bone formation was maintained in mildly diabetic mice at a similar level as non-diabetic controls, while the positive effects of exercise were nearly abolished in severely diabetic mice. At the cellular level, hyperglycemia reduced the sensitivity of osteocytes to mechanical stimulation and suppressed osteocytes’ secretion of proteins and signaling molecules that help build stronger bone.
“Our work demonstrates that diabetic bone can respond to exercise when the hyperglycemia is not severe, which suggests that mechanical interventions may be useful to improve bone health and reduce fracture risk in mildly affected diabetic patients,” Wang says.
The plan for collaboration between the University of Delaware and Christiana Care is to evaluate these research findings in humans and expand the research to include other complications of diabetes, such as cardiovascular disease. “The leading cause of death in America is cardiovascular disease, and the majority of people with diabetes will die from this,” Lenhard adds. http://www.newswise.com/articles/research-finds-link-between-diabetes-and-bone-health
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