Issue: February 2020
Disclosures: Clemente is founder and president of Levels Health. Einhorn reports he has served as a consultant for Sanofi. Kowalski is president and CEO of JDRF. Means is a medical advisor for Levels Health. Peters reports she has attended advisory boards for Abbott Diabetes Care (Libre) and has received research funding from Dexcom.
February 18, 2020
6 min read

Coming soon to your smartwatch: CGM for healthy adults

Issue: February 2020
Disclosures: Clemente is founder and president of Levels Health. Einhorn reports he has served as a consultant for Sanofi. Kowalski is president and CEO of JDRF. Means is a medical advisor for Levels Health. Peters reports she has attended advisory boards for Abbott Diabetes Care (Libre) and has received research funding from Dexcom.
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Continuous glucose monitors have revolutionized diabetes care since the first such device was approved by the FDA for personal use in 2005. Today, improvements in glucose sensor accuracy, smaller sensor size and ease of use have made it easier than ever for people with diabetes to monitor their blood glucose trends in real time — and Silicon Valley is taking notice.

Fitbit, Apple and Google are all reported to be investing in CGM technology, and dozens of smaller startups are developing CGM products aimed at adults without diabetes, according to industry experts. In 2018, Fitbit, which Google announced it would acquire last November, invested $6 million in the glucose monitoring startup Sano, which is developing a patented biometric sensor contained in a patch, according to the company’s website. In August 2018, AppleInsider reported on Apple’s patent application for a proprietary technique to noninvasively measure glucose with the Apple watch.

“People are hungry for objective data and feedback about what they are eating and doing, and how it is actually affecting their health,” Casey Means, MD, a medical advisor with Levels Health, a startup with a CGM-centered “health and wellness system” currently in development, told Endocrine Today. “CGM is the only real-time, quantitative and highly actionable data you can get about how your diet and lifestyle are affecting your health.”

Casey Means

Currently, four companies have FDA-cleared, personal CGM devices on the U.S. market that are available with a prescription for people with diabetes: Abbott (FreeStyle Libre), Dexcom (G4, G5, G6), Medtronic (Guardian Connect and Guardian Sensor 3) and Senseonics (Eversense). With several CGMs aimed at healthy adults already in development, the devices could soon become as common as activity trackers.

“It’s amazing for me to see, having been on a CGM myself with diabetes for 14 years now,” Aaron J. Kowalski, PhD, president and CEOof JDRF, told Endocrine Today. “Honestly, [the trend] makes good sense. We’re a country, and ultimately a globe, that is gaining weight, and one of the things that my brother and I learned when going on a CGM is that what you eat has a tremendous impact on your body. It is shocking to see in real time. I hear the same thing from people without diabetes.”


Interpreting ‘healthy’ glucose

Like a person with diabetes, a healthy person will likely observe a “spike” in blood glucose after consuming a Frappuccino or a pastry, Kowalski said.

Aaron J. Kowalski

“People imagine that people without diabetes have these 90 mg/dL glucoses and it’s a flat line all of the time,” Kowalski said. “It’s actually not that way.”

How such data can best serve healthy adults remains an issue of debate. In a study published in April in The Journal of Clinical Endocrinology & Metabolism, Viral Shah, MD, assistant professor of medicine and pediatrics at the Barbara Davis Center for Diabetes and the School of Medicine at the University of Colorado Anschutz Medical Campus, and colleagues wrote that there are limited data on CGM-measured glucose concentrations for people without diabetes. Most studies of CGM profiles among healthy, nondiabetic individuals have had small sample sizes or used early-generation CGM systems, which were less accurate than current devices, Shah and colleagues wrote.

To help establish references ranges for healthy people, the researchers analyzed data from 153 healthy children and adults without diabetes with a nonobese BMI, all family and friends of people with type 1 diabetes recruited to wear a blinded CGM with once-daily calibration (Dexcom G6) for up to 10 days. Researchers assessed mean glucose, hyperglycemia, hypoglycemia and glycemic variability.

The mean individual average glucose level was 98 mg/dL to 99 mg/dL for all age groups except those aged at least 60 years, for whom the mean average glucose was 104 mg/dL. The median time spent between 70 mg/dL and 140 mg/dL was 96%. The median time spent with glucose levels above 140 mg/dL was 2.1% (30 minutes per day). The median time spent with glucose levels below 70 mg/dL was 1.1% (15 minutes per day).

Daniel Einhorn

“While I am an absolute believer in full access to CGM for those with diabetes and prediabetes, and as a diagnostic tool for impaired glucose tolerance and to rule out hypoglycemia, I’m not sure what it means for healthy people,” Daniel Einhorn, MD, FACE, FACP, clinical professor of medicine at the University of California, San Diego, told Endocrine Today. “We don’t have norms for how high or low the occasional glucose goes in healthy people. We have no comprehensive studies to account for age, sex, race or other variables, so it’s not clear what CGM results will be actionable. That said, I would love to see research into what ‘normal’ CGM looks like and would support it.”

A growing trend

According to the research firm eMarketer, about 60 million Americans are wearing smartwatches, which now have the ability to track everything from steps, sleep patterns and heart rate to menstrual data for women. That trend is only expected to grow as more people become comfortable with wearable devices that track all types of behavior, including blood glucose data, Means said.


“This is a tool that is ready for prime time but currently sequestered to the diabetes realm,” Means said. “You need to have a diabetes diagnosis to get one. People are waking up to the fact that maybe we should start sooner with some of these tools.”

The idea of learning more about personal health through glucose readings drove Josh Clemente, the founder and president of Levels Health, to try wearing a CGM for the first time several years ago. The data he observed — he said a large portion of his day was spent in the prediabetes blood glucose range — led him to make lifestyle changes.

Josh Clemente

“That was the founding moment,” Clemente told Endocrine Today. “If we could take this amazing data stream, provide better context and actionable insight on top of it, this could change lives. I have completely renovated my lifestyle as a result of this device.”

Clemente said his company’s CGM system is still in beta testing, but confirmed that Levels Health will provide a “complete end-to-end experience” that enable real-time awareness of glucose levels with actionable insights and metrics to help members achieve positive dietary and lifestyle changes. A public launch is expected later this year, he said.

Anne L. Peters

For many who are excited by the idea of new health data, the devices cannot come soon enough. Anne L. Peters, MD, professor of clinical medicine at Keck School of Medicine at the University of Southern California, Los Angeles, said she often fields requests for CGM from healthy adults.

“I have put these on so many worried well people who can afford to pay for it,” Peters told Endocrine Today. “In Los Angeles, it’s already a thing. If you look at most of these tracings, they’re deadly dull, but occasionally, 1 in 10 surprises me with their glucose levels, and that leads me to recommend a glucose tolerance test. This is not going to help these healthy young people in Silicon Valley, but it may help if you put these on people in a clinic in Iowa to identify prediabetes more easily. That could make a difference and allow for more CV risk modification. Those are the people I would find it interesting to study, to see if an earlier diagnosis or earlier notice would make more of a difference.”

Kowalski said the more people who use CGM, regardless of diabetes status, the better it is for people with diabetes.


“One of the things we’ve been pushing at JDRF is clinical decision support — using this data to drive better diabetes management,” Kowalski said. “We know there are multiple forms of type 2 diabetes, and probably multiple forms of type 1 diabetes. Gathering this type of information can help drive the right therapies faster. The bigger the market size, the better it is for people with diabetes, because you’ll see better innovation and you’ll see competition, which drives costs down. That’s a good thing.”

Still, Kowalski said, the chief concern for diabetes stakeholders remains helping people with diabetes to get access to CGMs right now, at a time when the technology remains out of reach for many due to cost or insurance hurdles.

“It is frustrating when people with diabetes struggle for access right now,” Kowalski said. “This is a big struggle at JDRF and Helmsley, that these tools are still inaccessible for some folks. That’s a big fight for us. We have what is a lifesaving technology for people with diabetes, and we need to ensure that these new advances are accessible for everybody.” – by Regina Schaffer