For years, it has been widely known that obese people, and those with type 2 diabetes, tend to have higher bone density but also a higher risk of bone fractures. This paradox hasn’t been investigated or explained in great depth, so for this study, researchers were interested in looking at factors other than bone density that could affect a person’s fracture risk.
The study’s participants were 112 obese men, some of whom had type 2 diabetes. Researchers measured their body composition, bone density, bone turnover rate and bone strength, and also looked at their bone microarchitecture (bone structure at a microscopic level) using a variety of tools, including computed tomography (CT) scans. These results were compared with how the men fit into several categories based on their diabetes status and other metabolic measurements (such as cholesterol and triglycerides, also known as lipids): metabolically healthy (no abnormal lipid or glucose levels), metabolically unhealthy without diabetes, and metabolically unhealthy with type 2 diabetes.
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Type 2 diabetes and bone stregnth
The researchers found that compared with both metabolically healthy and metabolically unhealthy men without diabetes, those with type 2 had significantly lower levels of osteocalcin, a protein involved in bone mineralization, as well as another enzyme linked to bone turnover (called C-terminal telopeptide of type I collagen). Men with type 2 also had greater trabecular separation — indicating weaker bone structure — at their tibia (shin bone) and radius (a bone in the forearm), and they tended to have les stiffness in their tibia than men without diabetes.
While this study clearly shows that type 2 diabetes is linked to less bone turnover and weaker bone structure in obese men, it doesn’t explain what’s responsible for this connection. Higher blood glucose levels are known to cause many different types of dysfunction in cells throughout the body, and it’s possible that this includes cells that regulate bone mineralization. It’s also possible that certain behavioral or environmental factors — such as a person’s diet or exposure to toxins — could affect both the risk of developing type 2 and the risk of weaker bone structure.
But regardless of the causes, this study shows that people with type 2 are at greater risk for bone problems that aren’t seen in standard bone density tests. More researched is needed, the researchers note, to determine if people with diabetes could benefit from different types of screening to look for indicators of bone weakness, other than bone density.
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