Higher Fracture Risk Seen With Insulin Use in Type 2 Diabetes

Among people with type 2 diabetes, those who took insulin were more likely to experience major bone fractures, according to a new study presented at ENDO 2022, the annual meeting of the Endocrine Society, and described in an article at Endocrinology Network.

Bone fractures — especially when linked to osteoporosis (weaker, low-density bones) — can present a major health risk to older adults. Research shows that in older adults with type 2 diabetes, the risk for bone fractures is linked to blood glucose control — indicating that high blood glucose may cause damage to bones, just as it does to other tissues throughout the body. There has also been interest, though, in studying the role that certain medications may play in fracture risk — after all, people with higher blood glucose may be more likely to take multiple medications for diabetes and other health conditions. One recent study showed that one group of drugs — SGLT2 inhibitors, which are some of the most effective medications for type 2 diabetes — were not linked to a greater fracture risk for bone fractures, even though a previous study indicated that they might be.

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For the latest study, researchers looked at a database that included 6,694 people with type 2 diabetes ages 50 and older who took the same glucose-lowering medication for at least a year. The average age of participants was 65.8, and they were followed for a median of 6.1 years. During this period, the overall rate of major fractures related to osteoporosis was 8.36 per 1,000 person-years. More specifically, the overall rate of hip fractures was 1.53 per 1,000 person-years.

Participants were grouped according to which medication or medications they took — metformin alone, a sulfonylurea alone, insulin alone, metformin plus a DPP-4 inhibitor, metformin plus a sulfonylurea, metformin plus insulin, a sulfonylurea plus insulin, metformin plus a sulfonylurea and insulin, or a sulfonylurea plus insulin and a DPP-4 inhibitor.

Fractures more common among certain insulin users

Using participants who took metformin alone as a reference group, the researchers compared bone fracture risks between the groups. After adjusting for multiple factors known to affect fracture risk, the researchers found that compared with people who took metformin alone, those who took insulin were 1.96 times as likely to experience a major fracture related to osteoporosis and 3.06 times as likely to experience a hip fracture. No other medication was linked to a significantly higher fracture risk compared with metformin.

But when the researchers broke the data down further, they found that only insulin users with an A1C level (a measure of long-term blood glucose control) of 7% or higher or a body-mass index (BMI, a measure of body weight that takes height into account) of 25 or higher, indicating being overweight or obese.

The researchers concluded that while some insulin users appear to have an elevated risk for a major bone fracture, it’s not at all clear that taking insulin — rather than underlying traits — accounts for this risk. But the results, they noted, highlight the importance of bone density and fracture risk assessments in people with diabetes over age 50.

Want to learn more about maintaining healthy bones? Read “Better Bone Health With Diabetes,” “Boost Your Bone Health,” and “Diabetes, Bones.”