Many people with diabetes experiment with placement of their continuous glucose monitors and get good results, a new study finds.
A continuous glucose monitor is a sensor inserted under the skin that tracks blood sugar levels. People with type 1 diabetes -- and some with type 2 diabetes -- can use this near-constant stream of information to make decisions about eating, exercising and insulin dosing. (People with type 1 diabetes need synthetic insulin in order to use the sugar in food as fuel.)
To see where monitors were actually being worn, researchers culled social media posts for images of people using continuous glucose monitors made by Dexcom.
"This study identified that 64 percent of individuals in our sample were not wearing their Dexcom in an FDA-approved location," said Michelle Litchman, the study's lead author. She's an assistant professor at the University of Utah College of Nursing.
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Dexcom is one of a few continuous glucose monitors on the market. In adults, the U.S. Food and Drug Administration approved Dexcom monitors for use on the abdomen.
In children up to age 17, the device is approved for use on the abdomen and the upper buttocks, said Camilla Levister, a certified diabetes educator at the Mount Sinai Diabetes Center in New York City. Levister was not involved in the study.
Litchman said she noticed that her patients were wearing their monitors all over, and she wanted to know more about how well these non-FDA-approved sites worked.
She and her colleagues searched the social media site Instagram. They found 353 posts featuring people wearing Dexcom monitors.
Nearly two-thirds were wearing their monitor in a spot other than the FDA-approved location, Litchman said.
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Why do people move the devices around?
One reason is the need to avoid scar tissue. Another reason is for comfort. Also, the monitor should be moved to a different location on the abdomen every seven days, Litchman said. There's only so much "real estate" on the body, especially in children, she added.
The good news? "Failure rates were similar in the abdomen, outer arm and thigh," she noted.
The posterior arm -- towards the back of the arm, an area that tends to be slightly fatty -- was the most popular site, with almost 80 percent of people wearing the device there successfully, the findings showed.
Next in popularity was the abdomen, with a 77 percent success rate, followed by 69 percent success on the thigh.
More good news: These alternative sites were accurate, sometimes even more so than the abdomen. The sensor failure rate was 6.2 percent for the abdomen and only 2.2 percent on the outer arm and 3.3 percent on the thigh, the study found.
Litchman said people with type 1 diabetes seem to rely on social media posts to see other areas that people have tried. And they share information about what works and what doesn't.
Cynthia Rice is senior vice president for advocacy and policy at JDRF.
"It's very common to see [continuous glucose monitors] in different areas at JDRF events," she said.
Rice explained that the companies usually go to the FDA with a proposed use and the data that they have to support that request. Initially, she said, a drug or device indication is usually very limited, and then expands.
"But it's not against the law for people to use devices 'off-label' or for health care providers to prescribe them 'off-label,'" she noted. Off-label means in a manner different from the original indication.
Levister wasn't surprised by the study findings. She sees people use alternate sites all the time, she said. The one area she would caution against, however, is the calf.
"You want to be careful with the lower extremities and diabetes," Levister said. People with diabetes can get serious infections in the lower extremities, so it's better not to rely on that area, she explained.
Litchman's advice? "If someone is interested in trying a different location, they may want to ask their health care providers about the pros and cons of other sites," she said.
The study was presented Sunday at the American Association of Diabetes Educators meeting in Indianapolis. Research presented at meetings is usually considered preliminary until published in a peer-reviewed medical journal.
More information
Learn more about continuous glucose monitors from the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.
