Study Eases Concern That Common Diabetes Med Might Harm Bones

THURSDAY, Jan. 3, 2019 (HealthDay News) -- If you have type 2 diabetes and you're taking canagliflozin to help control your blood sugar, a new study has some good news for you: The drug doesn't appear to raise the risk of bone fractures.

Previously, research had suggested this might be the case.

"We were interested in doing this study because there was one randomized trial that said there was an increased risk of bone fractures and another that said there wasn't. So, we conducted a real-world study with almost 200,000 people with type 2 diabetes," said study author Dr. Michael Fralick.

"I hope these findings are reassuring to patients and physicians because these are blockbuster medications for type 2 diabetes. This class of medicines can improve blood sugar levels and help reduce heart disease risk," he said. Fralick is from the division of pharmacoepidemiology and pharmacoeconomics at Brigham and Women's Hospital in Boston, and a general internist at the University of Toronto.

Canagliflozin (Invokana, Invokamet) is one drug in a class of medications called SGLT-2 inhibitors. Other drugs in this class include dapagliflozin (Farxiga) and empagliflozin (Jardiance).

These drugs cause the kidneys to remove excess sugar from the blood and excrete it through urine, which lowers blood sugar levels, according to the U.S. Food and Drug Administration. This class of drugs has been linked to a number of complications, including kidney injury and serious genital infections.

Fralick said one way these drugs could potentially increase fracture risk is by lowering bone mineral density.

Dr. William Leslie, author of an editorial accompanying the study, suggested that dehydration may be another way these drugs might be linked to fracture risk. Leslie is a professor of medicine and radiology at the University of Manitoba in Canada.

For the new report, Fralick and his team reviewed data from two U.S. commercial health care databases. They found information on about 200,000 people with type 2 diabetes who were just starting to take one of two different type 2 diabetes medications -- canagliflozin or a medication in a class of drugs called GLP-1 agonists, which includes Victoza, Trulicity and Byetta. These drugs haven't been linked to an increased risk of fractures.

The researchers looked for fractures in the upper and lower arms, as well as the hips and pelvis.

In the end, the study team compared approximately 80,000 people on canagliflozin to about 80,000 treated with GLP-1 agonists. The patients' average age was 55, and about 48 percent were female.

The study showed a similar risk of fractures in these low-risk, middle-aged populations.

Both Fralick and Leslie said the jury is still out for people who are at a higher risk of fractures, such as elderly people.

This study is "a relatively low-risk population. But, it begs the question, what about higher-risk populations? We need additional safety data," Leslie said.

The U.S. Food and Drug Administration currently requires canagliflozin labels to carry a warning about the potential fracture risk, and Fralick said it may be too soon to change the labeling, particularly for people at high risk. Both experts said more research is needed.

In the meantime, if you're concerned about taking canagliflozin, Fralick recommended having a conversation with your health care provider. But, he added, "For people without a high baseline risk, the risk of fracture is very small and the clear benefits to SGLT-2s outweigh that potential risk."

The findings were published online Jan. 1 in the Annals of Internal Medicine.

More information

Learn more about oral diabetes medications from the American Diabetes Association.