Dallas Waldon doesn’t have diabetes, but she says she benefits from continuous glucose monitoring (CGM). “I’m a huge fan of CGMs and used them before, during, and after my pregnancy, [up to] 6 months postpartum, I’m down 11 pounds from my prepregnancy weight,” said Ms. Waldon, a manager for a land-buying company who lives in El Dorado, Calif.
“CGMs bring a certain level of accountability to what you’re eating. You can’t pretend you didn’t eat that cookie while making the kids’ lunch, or that the latte you had was ‘just coffee,’ ” she said. “You have the hard numbers to answer to, and that makes you think twice before putting anything in your mouth.”
Ms. Waldon is not alone. Although CGMs are typically used by people with type 1 diabetes, and increasingly those with type 2 diabetes, some endocrinologists say they are seeing an increased demand for CGM use from individuals who don’t have diabetes.
This allows users to monitor the glucose level and see how eating and exercise affects it. The companies claim that CGM use will help motivate individuals to eat better and maximize their exercise, and therefore consequently lose weight.
These lifestyle programs typically offer users the FreeStyle Libre (Abbott Laboratories). It uses a coin-sized sensor, generally worn on the upper arm, which lasts 14 days and measures glucose in the interstitial fluid. Users can read their glucose levels via an app on their smartphones as many times a day as they want. The FreeStyle Libre is worn by many people with diabetes and is a simple CGM to use, said Anne Peters, MD, professor of clinical medicine, University of Southern California, Los Angeles.
This growing demand for CGM use among healthy people is driven by an increasing “fascination” for monitoring every bodily function, as can be seen by the popularity of smart devices such as Fitbits and Apple watches, Dr. Peters added. These devices allow users to see their heart rates, review their sleep patterns, and monitor their pulses in real time; a CGM is an extension of that by providing up-to-the-minute glucose monitoring.
‘Everyone wants a CGM’
“Everyone wants a CGM,” Dr. Peters said, noting that even family members of her patients with diabetes are asking for them. She admits that their use can be effective for those who are prediabetic so they can see their glycemic responses to food. For instance, someone who typically eats oatmeal for breakfast may see their blood glucose increase, meaning they might want to lower their carbs.
David Klonoff, MD, medical director of the Diabetes Research Institute, Mills-Peninsula Medical Center, San Mateo, Calif., agrees that there has been an increase in use by people who don’t have diabetes as CGMs offer information they wouldn’t otherwise have access to “without having to prick themselves many times.”
People are using CGMs to monitor how high their blood glucose rises after eating certain foods, the length of time it takes to reach peak levels, and how quickly levels drop, he added. Elite athletes are using CGMs to ensure that they are consuming enough calories to avoid hypoglycemia, Dr. Klonoff said.
David T. Ahn, MD, program director at the Mary & Dick Allen Diabetes Center at Hoag Hospital in Newport Beach, Calif., also believes that the devices can provide useful information. “I find that CGM helps people learn a lot about nutrition and how lifestyle choices like food, activity, and stress impact their own physiology,” he stated.
Dr. David T. Ahn
“For example, comparing glucose spikes after different [types of] meals can deepen people’s understanding of carbohydrates vs. protein, or high glycemic index foods vs. low glycemic index foods,” he continued. “In addition, if a patient chooses to follow a very low-carbohydrate diet and/or an intermittent fasting diet, a CGM can be a powerful tool to measure consistency with that lifestyle choice.”
And for a person without diabetes, wearing a CGM provides a way to have personalized information on other physiologic measures, part of the quantified self movement where users log and track their blood pressure, urine output, and oxygen saturation, among other things, Dr. Klonoff said.
But does knowing all this result in behavioral changes?
Dr. Ahn isn’t sure. “For many people, being able to see glucose excursions throughout the day and after meals can be extremely educational and motivating. But much like the Fitbit or Apple Watch, simply wearing [a CGM] ... does not translate to behavior change. The CGM data patterns in someone without diabetes can start to become predictable over time, leading to a drop-off in utility/adherence after the initial education period,” he said.
Dr. Peters said she too isn’t convinced about the long-term worth of CGM in promoting or sustaining behavioral change, as the “novelty” of tracking may wear off after a few months.
And there’s no scientific proof that CGM use in those without diabetes has any impact.
“While there are many programs that offer coaching with CGM data, we need more studies to determine if this leads to improved outcomes like weight loss and prevention, or delay in the development of diabetes,” said Diana Isaacs, PharmD, BCPS, BCACP, BC-ADM, CDCES, FADCES, FCCP, director of education and training in diabetes technology at Cleveland Clinic Diabetes Center.
Diana Isaacs, PharmD
A 2019 study published in the Journal of Clinical Endocrinology and Metabolism found that the blood glucose of individuals without diabetes using a CGM was in the “ideal” range between 70 mg/dL and 140 mg/dL 96% of the time. “Their glucose was beautifully controlled,” said Dr. Peters, who was one of the study authors.
Currently there aren’t any studies evaluating patterns among healthy individuals wearing CGMs, Dr. Klonoff noted, but he predicts that those studies will be done in the future to examine metabolic patterns that might contribute to someone developing prediabetes or diabetes.
“More data are needed from studies that focus on individuals at risk for diabetes to better understand the role of CGM in these cases, and how to best interpret and utilize the results,” said Fida Bacha, MD, a diabetes and endocrinology specialist and associate professor of pediatrics at Baylor College of Medicine in Houston.
“If clear metrics are identified to predict the progression to diabetes, then this would be worthwhile for early detection and prevention of the disease,” Dr. Bacha said.