Conference Coverage

Continuous glucose monitors aren’t just for abdomens anymore



Close to two-thirds of people with diabetes who wear a continuous glucose monitor position it on an area of the body other than the abdomen, the only site sanctioned by the device’s manufacturer and federal authorities. And that lack of compliance has resulted in no apparent ill effects, according to a new study of related social media.

Michelle L. Litchman, PhD, of the University of Utah in Salt Lake City, and her colleagues, examined nearly 3,000 online postings of photos of continuous glucose monitors (CGM) manufactured by Dexcom, currently the most popular brand of CGMs in the United States. The results of their study, presented at this year’s annual meeting of the American Association of Diabetes Educators, showed that about 74% of device-wearing patients place it on the upper arm, thigh, buttocks, or back, rather than the abdomen, as indicated by the Food and Drug Administration. The device is indicated for use on the abdomen in adults because that was the only location used for the clinical studies of the device, Dr. Litchman explained in an interview.

Michelle Litchman, PhD, of the University of Utah, Salt Lake City

Dr. Michelle Litchman

The FDA should consider approving CGMs for use elsewhere on the body, since based on the online comments of CGM users, the device’s sensor failed in 32 users and failure was equally likely to occur in people who used CGMs by the book as in those who wore it where they preferred to. Failure was described in the study as the device displaying blood sugar levels inaccurately, or in a “nonmeaningful” way. Typically, if a sensor fails, the wearer recalibrates it, or if necessary, replaces the device, often moving it to another place on the body. “Our research suggests people are wearing their CGM devices on areas other than the abdomen and don’t appear to be having problems,” Dr. Litchman said.

Overall, out of 2,923 Instagram posts concerning the Dexcom CGM device, Dr. Litchman and her fellow investigators culled 353 photos of the device being worn on the body. Of these, 26.1% indicated the device was placed according to FDA guidance, while 63.7% of the remaining photos depicted the device placed on the inner arm, the forearm, thigh, calf, buttock, or back. In just over 10% of the photos, the device’s location on the body was unclear. Dr. Litchman and her colleagues concluded that when the device was worn according to directions, the failure rate was 6.2%. When placed on the outer arm it had a 2.2% failure rate, and there was a 3.3% failure rate when the device was worn on the thigh.

Since the combined nonabdomen and abdomen failure rates were similar, Dr. Litchman suggested any noncompliance was simply pragmatism. Although the CGM is meant to be relocated weekly around the abdomen, that is also the area of the body typically used for insulin injections several times a day, often resulting in scar tissue build-up that lessens insulin absorption. “It boils down to how much real estate someone has for effective insulin administration,” Dr. Litchman noted. “Individuals with diabetes need to protect the sites where they will inject insulin for the rest of their lives.”

For tips on how to do this effectively, Dr. Litchman said people with diabetes increasingly turn to online communities.

“There are differences in the FDA-approved, by the book, information patients are given and what they do in real life. While some may view this as a threat, I like to see this as opportunity to learn from patients. Patients are finding successes outside of [official instructions], therefore, we should be seeking out this experiential evidence. This research is a start to better understanding the safety related to CGM use in sites other than the abdomen,” she said in the interview.

Dr. Litchman reported that she had no conflict of interest to disclose.

On Twitter @whitneymcknight

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