Dec. 12, 2023 — Wearable technology has been a game-changer for consumers. From rings and watches to wristbands, patches, and clothing, information that once required a bunch of confusing calculations is now available anytime, anywhere with a flick of the wrist or a glance at a smartphone.
Continuous glucose monitors – devices that help people with diabetes avoid dangerous and extreme changes in blood sugar levels – are among the most recent wearables to grab attention. Approved by the FDA for use in diabetes, millions of consumers are jumping on the CGM bandwagon with encouragement from social media influencers and promises of improved athletic performance, weight loss, and metabolic health.
Before you join the masses and purchase one of these devices, know that diabetes experts are unified in their concerns that CGMs are not quite ready for the consumer market for people who don’t have diabetes but want to try and monitor their blood sugar anyway.
“If you look across history, there’s been many instances where large volumes of people have followed something that ended up not being correct,” said Tamara Oser, MD, director of the primary care diabetes lab at the University of Colorado Anschutz School of Medicine in Aurora.
Despite their rising popularity, Oser said “we need to be mindful that we don’t have really strong evidence yet that they are going to cause a change in outcomes,” she said.
Highs and Lows
Blood sugar spikes after meals are a normal phenomenon.
“They go up, your body responds within 15 to 30 minutes, and then it gradually goes down. That is a normal process,” said Marc Kai, MD, an internist at Mercy Medical Center in Baltimore. “In someone with diabetes, the number may go higher, last longer, and take longer to go back down to normal; that’s why we use these monitors: so we can see what and when it is happening.”
The challenge comes when a person who doesn’t have diabetes takes this information and reinterprets it to fit what is often an incomplete narrative.
“Many companies that sell CGMs and the apps are taking data from their customers and making generalizations, and that’s just inappropriate,” says Danielle Omar, a registered dietitian and nutrition consultant based in Northern Virginia. An example is eating oatmeal, which one social media influencer compares to being “chased by a Siberian tiger.”
Some people were seeing data that showed their blood sugar spiked after eating oatmeal. “But that’s just the way your body works; you just ate a carbohydrate,” she said.
“There’s so many factors,” Omar said. “What was in the oatmeal, what kind of oatmeal was it? “Was it quick oats, steel cut, or overnight oats? What was in it? Was it sugar or jelly? A banana? Oat milk? You know, there are so many things that might have been the real reason why their blood sugar spiked.”
Omar’s concerns are not unfounded. David Lam, MD, an endocrinologist and associate professor at Icahn School of Medicine at Mount Sinai in New York City, said “it’s natural to have a glucose excursion. Although CGMs can probably inform people what their baseline might be and give positive reinforcement to reduce caloric intake, I don’t know if they convey any advantage compared to a registered dietitian’s advice.”
What CGMs Do and Don’t
Continuous glucose monitors were first developed in the 1990s to help patients with type 1 diabetes and are now used in certain type 2 diabetes patients as well. Researchers are also looking into the benefits for other groups, including people with prediabetes and elite athletes. Still, these devices are not without limitations, nor are they suitable for everyone.
Lam says that he uses the monitors in his patients with diabetes but not broadly.
“It’s an individualized treatment decision,” he says. “Just because the technology exists and is FDA-approved for specific medical conditions, it doesn’t mean that everyone can be on them. When I prescribe a CGM for my patients, it’s always with a discussion about what it can offer, what it does, what its limitations are, and how I think it could help with their care.”
So what specifically do these devices do?
“CGMs provide an estimation of someone’s blood glucose in that moment,” Lam said, noting that the measurement can help a person avoid dangerous and often life-threatening declines in blood sugar, or persistent and equally dangerous highs. This is different to more traditional measurements like the A1c blood test, which measures average blood sugar levels over a 3-month period.
Unlike a finger prick, which measures the sugar concentration in blood, “CGMs measure the sugar concentration in the tissues just outside the bloodstream – the ‘interstitial’ fluid and state that exists in the tissues,” Kai said. “Basic science dictates that it’s going to be about the same.”
He said that when someone has diabetes or insulin issues, spikes in blood sugar that normally occur after eating tend to last longer and take longer to return to normal. Knowing this information, which is called “time in range,” can help shape behavior (e.g., avoiding certain desserts) and guide treatments or changes in diet and lifestyle.
What You Need to Know
There’s no doubt that there is probably a place for continuous glucose monitors in the non-diabetes consumer market in the foreseeable future. Fernando Ovalle, MD, an endocrinologist, professor, and director of the University of Alabama-Birmingham’s Diabetes & Endocrine Clinical Research Unit, said at least a fourth of the population is at risk for developing diabetes, 20% of whom may be slowly developing it over their lifetime. “The question is, how many of those people can you help avoid or delay it, or if not avoid it, at least improve it?”
Ovalle said more research is needed so “we’ll be able to know what’s truly normal and truly abnormal beyond the glucose tolerance test.”
At least for now, the technology needs to improve. Oser said not only do readings differ between CGM devices, but that they are less accurate at the lower versus normal or high levels.
There’s also the danger of “false lows.”
“I have a patient without diabetes or prediabetes whose CGM flashed a low blood sugar reading. She got so alarmed, she went to the emergency room and it was a false low,” Osler said. Things like incorrect placement on the body, dehydration, and even skin trauma where you place it can also influence accuracy.
Another important consideration is that food is not the only factor that can impact blood sugar levels. “Glucose is really a window into physiology,” Lam said. “Outside of the obvious, exercise, different stressors (including illness), hormones that help bodies fight infection, sleep, medications, all of these things can increase insulin resistance and glucose levels.”
One of the potential pitfalls of a healthy person using a continuous glucose monitor is information overload, Kai said.
“Blood sugar varies from person to person, so folks are going to look up numbers and worry when in fact, for their physiology, their personal body, their own personal metabolism, the response is perfectly normal,” he said.
If you are still interested in trying a continuous glucose monitor, at the very least, contact your doctor or a dietitian who can help you understand what the numbers are telling you and how you can harness them in a way that makes sense for your personal health.