People with type 2 diabetes can face a puzzling bone problem.
Their bones often look as dense as, or even denser than, those of people without diabetes, yet they may still be more likely to suffer a fracture.
A new study suggests that ordinary bone loss does not fully explain this higher risk. The research was published in Diabetes Care and used data from the long-running Framingham Study.
The study was led by researchers including Alyssa B. Dufour of the Hinda and Arthur Marcus Institute for Aging Research at Hebrew SeniorLife. Dufour is also an instructor in medicine at Harvard Medical School and Beth Israel Deaconess Medical Center.
Bone is living tissue that is constantly being broken down and rebuilt. As people grow older, this balance can shift, and bones may gradually become weaker.
Doctors often estimate fracture risk by measuring bone mineral density. Lower density can be a warning sign for osteoporosis, a condition in which bones become fragile and more likely to break.
But type 2 diabetes creates an unusual situation. Many people with the disease do not have especially low bone density, yet research has repeatedly shown that some have a greater risk of fractures.
This has led scientists to ask whether the internal structure of bone changes differently in people with diabetes. Bone is not a solid block of material and contains different layers with different jobs.
The outer part, called cortical bone, is hard and compact. It forms a strong shell around bones and provides much of their ability to withstand force.
Inside is trabecular bone, a lighter network with a sponge-like structure. This inner framework also contributes to strength and helps bones cope with everyday stresses.
In the new study, researchers used advanced bone imaging to examine both of these areas in older adults. The technology allowed them to look beyond standard bone density and study small-scale changes in bone structure and estimated strength.
The researchers expected people with type 2 diabetes to show greater deterioration over time. If that had happened, it could have helped explain why fractures occur more often in this group.
Instead, they found that bone loss was broadly similar in older adults with and without type 2 diabetes. Changes in the small structure and strength of the bones did not provide the simple explanation the researchers had expected.
This finding adds to what scientists sometimes call the diabetes-bone paradox. People with type 2 diabetes can have relatively dense bones while still experiencing fractures at higher rates.
Senior author Elizabeth Samelson said this shows why bone density cannot tell the entire story. Other factors may affect whether a person with diabetes is likely to break a bone.
One possible factor is the quality of bone tissue rather than simply how much mineral it contains. Long-term high blood sugar may affect proteins within bone and change its material properties in ways that standard density measurements do not fully capture.
Diabetes can also affect fracture risk outside the skeleton itself. Nerve damage may reduce feeling in the feet, vision problems can make obstacles harder to see, and muscle weakness or balance problems can increase the chance of falling.
Some older adults with diabetes also take several medicines or have other health conditions that may contribute to dizziness, weakness or falls. A fracture happens when bone strength and the force placed on the bone come together, so fall risk is an important part of the picture.
The study is valuable because it followed changes over time instead of looking at participants only once. It also used detailed imaging capable of examining parts of bone that ordinary density tests cannot show as clearly.
However, the results do not prove that bone structure is unimportant in diabetes. Rather, they suggest that the rate of age-related bone loss measured in this study is unlikely to be the only reason for the increased fracture risk.
More research is needed to examine other possibilities, including the quality of bone material, the effects of blood sugar over many years, diabetes complications, medications and differences in falls. These factors may work together rather than acting independently.
For patients, the study is a reminder that a reassuring bone density result does not necessarily capture every aspect of fracture risk. Older adults with type 2 diabetes may benefit from attention not only to bone health but also to strength, balance, vision, foot sensation and ways to prevent falls.
Overall, the research helps narrow the search for the cause of higher fracture risk in type 2 diabetes. It rules against one simple explanation: that these patients merely lose bone faster as they age.
The study therefore moves the field toward a broader view of bone health. Understanding why apparently dense bones can still break may eventually help doctors identify high-risk patients more accurately and develop better ways to prevent fractures.
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Source: Hebrew SeniorLife.
