Ann V. Schwartz, PhD, is a professor of epidemiology and biostatistics at the University of California, San Francisco, School of Medicine. As an expert in bone health in people with diabetes, she shares her insights on the risk of fractures and other bone problems in people with type 1 and type 2 diabetes and offers advice on screening and prevention.

Q: Are people with diabetes at higher risk of bone problems than people without diabetes?

A: Yes, both men and women with diabetes—primarily those in middle age and older—have more bone problems than people without diabetes. These problems include fractures, which are major causes of disability in the United States, so it’s an important public health concern.

Older adults are especially at risk for fractures, in part because they are more likely to fall than younger adults. The risk is particularly obvious in older adults with type 1 diabetes. For example, their risk of hip fracture is 500% higher than for older adults without diabetes. The risk is more modest in older adults with type 2 diabetes, about 30% higher.

Q: Why do people with diabetes sometimes develop bone problems?

A: The exact mechanisms for poor bone health in people with diabetes are unclear. For a given bone mineral density (BMD), diabetic bone tends to be more fragile, and there’s a lot of research going on to figure out why. It’s possible that changes in bone metabolism and structure, as well as BMD, may worsen bone quality.

One factor is the use of thiazolidinediones (TZDs), medicines for people with type 2 diabetes, which double the risk of fracture in women. Health care professionals would not want to use a TZD in a patient who’s already at high risk of fracture. Other possible mechanisms include

• an accumulation of advanced glycation end products (AGEs), the end result of reactions between protein and sugar. AGEs accumulate in bone collagen and can weaken the material properties of bone.
• vascular dysfunction. There’s a hypothesis that diabetes negatively impacts bone vasculature, which may lead to problems like greater porosity of cortical bone—the protective outer layer of bone.

Q: Do these problems differ between people with type 1 versus type 2 diabetes?

A: Type 1 and type 2 diabetes have different effects on BMD, but both can lead to fragile bones. People with type 1 diabetes often have lower BMD than those without diabetes, so their risk for fracture is higher, as expected. However, their lower bone density doesn’t entirely account for their increased fracture risk. Other factors—such as long-standing disease, blood glucose levels outside the target range, and taking insulin—may play a role, too. Our understanding of how these factors may interact is unclear.

In type 2 diabetes, you have this strange situation in which many people have similar or higher BMD than people without the disease but are still at increased risk for fractures. That’s led to a search for underlying mechanisms beyond BMD that make bone more fragile. It’s worth noting that people with diabetes are at higher risk of falling than people without the disease, and that is probably another reason for higher fracture risk.

Q: What indicators of bone problems should health care professionals look for?

A: People with diabetes have the same risk factors for fracture as all adults. These risk factors include low BMD, falls, older age, being female, prior fracture, low body mass index, reduced physical activity, use of glucocorticoids, smoking, and consuming too much alcohol.

In patients with diabetes, there are other risk factors to look for, like having the disease for 5 years or longer and high glucose levels. If patients have hypoglycemia, that’s also going to increase their risk for falls and fractures.

We also know that some diabetes complications are associated with higher fall and fracture risk. These complications include peripheral neuropathy, poor vision, muscle weakness, and kidney disease. They are all targets for treatment.

Q: What tests can health care professionals recommend for their patients with diabetes?

A: It’s important for patients with diabetes to get a DEXA (dual-energy x-ray absorptiometry) scan, the standard test for BMD that predicts fracture over the next 5 years. You want to identify who’s at the highest and lowest risk, and DEXA does that beautifully in people with and without diabetes.

For example, in people without diabetes, a T-score of -2.5 or lower indicates osteoporosis; a score of -2.5 to -1.0 is osteopenia. For people without diabetes, pharmacological therapy to prevent fractures would be considered with a T-score below -2.5. However, in people with diabetes, DEXA tends to underestimate fracture risk. Health care professionals can easily account for that by using a T-score of -2.0 instead of -2.5 as the cutoff. That’s the point where they should consider pharmacological therapy in a patient with diabetes. Similarly, when using FRAX, a companion tool for estimating fracture risk, decrease the entered T-score by 0.5. So, if a patient with diabetes has a T-score of -2.0, use -2.5.

The accuracy of predicting patient risk with FRAX may be improved by adding a trabecular bone score (TBS), an index of bone microarchitecture derived from lumbar spine DEXA, but it’s not necessary. Adults with diabetes have a lower TBS than those without diabetes, so TBS can improve fracture prediction in people with diabetes compared with BMD alone.

It’s important to know that people with type 1 diabetes have a higher risk of fracture , so they should get regular DEXA scans. There are no specific guidelines on when to start; however, some pediatric endocrinologists recommend starting DEXA scans as early as adolescence if there are other risk factors. It’s up to the health care professional’s judgment. 

Q: How can patients prevent or at least minimize bone problems? Does glycemic control help?

A: We are pretty sure that glycemic control that is not in the target range increases the risk for fracture. ACCORD BONE, an ACCORD ancillary study in people with type 2 diabetes, showed no significant difference in the rate of falls, nonspine fractures, or BMD in participants who had tight glycemic control (median A1C, 6.4%) versus those who had standard glycemic control (median A1C, 7.5%). A limitation of this study was that we compared standard control with intensive control. But in observational studies, people with A1C levels of 8% or higher do have increased fracture risk, compared with people whose A1C level is in the 6-7% range.

The message is that glucose levels outside the target range increase fracture risk, so you want to get a patient’s A1C level in a solid range. If you’re worried about increasing the risk for hypoglycemia in older adults, it may not be that important to get tight control.

Preventing falls and promoting bone strength can help prevent fractures. Recommendations for patients include getting regular physical activity, including weight-bearing exercise like walking and resistance exercise like lifting weights. Proper nutrition, including adequate calcium and vitamin D intake from food and, if needed, supplements, also helps.

There are no drugs specifically approved to treat osteoporosis in people with diabetes, so health care professionals can follow general guidelines for treatment of osteoporosis. Bisphosphonates, the first-line treatment for osteoporosis, are effective in preventing bone loss and reducing fracture risk in people with diabetes.

Do you screen your patients for bone complications? Share below in the comments.