The recent US Food and Drug Administration (FDA) clearance of two over-the-counter (OTC) continuous glucose monitors (CGMs) — Dexcom’s Stelo and Abbott’s Lingo — has sparked interest in potentially expanding their use to those without diabetes or prediabetes.
There are several valid questions about how the general population might benefit from CGMs. Can they motivate those struggling with overweight to shed pounds? Would they prompt users to follow more healthful eating patterns? Can they act as a canary in the coal mine, alerting users to prediabetes?
The short answer to these questions is, we don’t know.
“Glucose levels fluctuate in everyone in response to meals, exercise, stress, etc, but there has been no credible research to support CGM use by most people who do not have diabetes,” Jill Crandall, MD, chief of endocrinology at Albert Einstein College of Medicine and Montefiore Health System in New York City, said in an interview.
“The utility of CGM for people without diabetes hasn’t been established and the drive to market CGM as an OTC device seems largely driven by financial considerations,” Crandall said. She advocates instead for a strategy directed at more meaningful objectives.
“For now, efforts should be focused on making CGMs available to patients who will clearly benefit — ie, people with diabetes, especially those who are using insulin and those who are struggling to achieve desired levels of glucose control.”
Nicole Spartano, PhD, assistant professor of medicine in endocrinology, diabetes, nutrition and weight management at Boston University’s Chobanian & Avedisian School of Medicine in Massachusetts, agreed with this assessment.
“It is definitely too early to make recommendations for patients without diabetes based on their CGM data,” said Spartano, who also serves as the director of the Glucose Monitoring Station at the Framingham Heart Study in Framingham, Massachusetts. “We simply do not have enough follow-up data to tell us which CGM metrics are associated with higher risk for disease.”
Spartano served as the lead author of a recent study showing time spent in various CGM ranges in a large cohort of individuals without diabetes using the Dexcom G6 Pro model. In the future, she said the data may be used to establish reference ranges for clinicians and individuals.
“We are working on another paper surveying diabetologists and CGM experts about how they interpret CGM reports from individuals without diabetes,” she said in an interview. Although the data are not yet published, Spartano said, “we are finding that clinicians are currently very discordant in how they interpret these reports.”
Potential Benefits Right Now
Satish Garg, MD, director of the Adult Clinic at the Barbara Davis Center for Diabetes at the University of Colorado Anschutz Medical Campus, Aurora, and editor-in-chief of Diabetes Technology & Therapeutics, is convinced that glucose should be considered another vital sign, like blood pressure, pulse rate, respiration rate, and body temperature. Therefore, he sees the use of a CGM in people without diabetes as a way to build awareness and perhaps prompt behavior modification.
“Someone with an A1c of 4.9 on a normal day may notice that they’ve gained a little bit of weight, and if they use an OTC CGM and start seeing changes, it might help them to modulate their diet themselves, whether they see a dietitian or not,” Garg said.
He gave the example of “a natural behavioral change” occurring when someone using a CGM declines to eat a post-meal dessert after seeing their blood glucose had already risen to 170.
Wearing a CGM also has the potential to alert the user to high blood glucose, leading them to an earlier diagnosis of prediabetes or diabetes, Shichun Bao, MD, PhD, Diabetes Technology Program Leader at the Vanderbilt Eskind Diabetes Clinic of Vanderbilt University in Nashville, Tennessee, said in an interview. She has had cases where a family member of someone with diabetes used the patient’s fingerstick meter, found that their glucose was 280, and self-diagnosed with diabetes.
“It’s the same thing with the CGM,” she said. “If they somehow did not know they have diabetes and they wear a CGM and it shows their sugar is high, that will help them to know to see their provider to get a diagnosis, get treated, and track progression.”
Given the shortage of endocrinologists and long waits for appointments in the United States and elsewhere, it is very likely that primary care physicians will be the ones fielding questions from individuals without diabetes interested in purchasing an OTC CGM. Internist Douglas Paauw, MD, a professor at the University of Washington School of Medicine, Seattle, said in an interview that, for his practice, “the benefits outweigh some of the limitations.”
“I don’t really think somebody who doesn’t have diabetes needs to be using a CGM all the time or long term,” he said. “But I have used it in a few people without diabetes, and I think if someone can afford to use it for 2-4 weeks, especially if they’ve been gaining weight, then they can really recognize what happens to their bodies when they eat certain foods.”
Paauw added that CGMs are a more effective means of teaching his patients than them receiving a lecture from him on healthy eating. “There’s nothing like immediate feedback on what happens to your body to change behavior.”
Similarly, William Golden, medical director at Arkansas Medicaid and professor of medicine and public health at the University of Arkansas for Medical Sciences, Little Rock, said in an interview that “it is difficult to justify coverage for CGMs on demand — but if people want to invest in their own devices and the technology motivates them to eat better and/or lose weight, then there are benefits to be had.”