For about a month, Tabb Firchau, an entrepreneur living in Seattle, has been wearing a continuous glucose monitor (CGM), a federally approved medical device that tracks blood sugar levels for people with diabetes. The CGM patch has a small needle that probes the inside of his arm, and a sensor that tracks changes to his blood sugar in real-time. The data is then sent to his smartphone.
Firchau bought his CGM off eBay for about $300. “I track almost everything, from sleep to exercise,” says Firchau. “I’ve been trying to learn why some days I feel fantastic, and other days I don’t. I had a cinnamon roll recently and my blood glucose doubled in 60 minutes. The monitor helps you understand the costs of the decisions you are making.”
He couldn’t get one from his doctor, because Firchau doesn’t actually have diabetes. Rather, he’s part of a small but growing group of people who are wearing CGMs to track—and then hack—what goes on in their own bodies. And if enterprising startups like Sano Intelligence, which Gizmodo wrote about in February, are successful, a CGM marketed to the general public may not that be far off.
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A healthy person wearing a diabetes device may seem odd, but in the quantified-self movement, people like Firchau say it makes sense to track their blood sugar, especially given all the recent attention to the risks associated with overconsumption of sugar and processed carbohydrates, like diabetes, heart disease, and obesity.
Everyone’s blood sugar levels change throughout the day, and especially after they eat, but those fluctuations are important to track for people with diabetes, since their body doesn’t regulate blood sugar on its own. For people without diabetes, however, the pancreas naturally releases insulin to keep levels in check.
Since the first CGM was approved in 2005, some people with diabetes have used the devices to help monitor their blood sugar, rather than take finger pricks throughout the day to check it manually. The devices take a measurement every one to five minutes, and people can set alarms to alert them whenever their levels are dangerously high or low.
“I think it’s chuckle-worthy and interesting that a diabetes tool would make its way mainstream,” says Aaron Kowalski, chief mission officer at the diabetes nonprofit JDRF, who also has type 1 diabetes. “ But I guarantee if you wore one to McDonald’s, your blood sugar would spike and you’d learn a lot about nutrition.”
Using a CGM, even when it’s medically necessary, is not cheap. Parts of the device have to be replaced every couple of weeks or months and it’s estimated that CGMs cost $5–10 per day, or around $3,000 a year. For people with type 1 diabetes, that can be covered by insurance. But people without the disease must either convince a doctor to prescribe one or purchase them online on sites like eBay. Even if a doctor prescribes one, it’s highly unlikely insurance would cover it for someone without diabetes.
Five diabetes experts I spoke with for this story do not think the trend is dangerous. Though a CGM is attached to the wearer’s body, it’s considered a minimally invasive device. “I don’t think there’s any risk,” says Boris Kovatchev, director of the University of Virginia (UVA) Center for Diabetes Technology. “Unless people get too fixated.”
Some doctors who don’t have diabetes even wear CGMs themselves. Dr. Steven Russell, a diabetes expert at the Massachusetts General Hospital in Boston, and his research collaborator Dr. Ed Damiano of Boston University, say they wear CGM monitors semi-regularly for demonstration purposes and to test new versions—and they learn a lot each time.
“I am fascinated to see how my blood glucose changes after different meals,” says Russell. “You look at that muffin and remember what it did your blood glucose, and make a different choice. There’s no reason why people without diabetes wouldn’t be interested that.”
During a particularly stressful point in his life, Damiano—who is quite far along in developing and bringing to market a bionic pancreas—says he noticed his blood sugar running higher than normal. “It was a clear indication that stress has an impact on you, even without diabetes,” he says. “It caused me to make a deliberate decision to deal with [the stress].”
Exercise is known to be helpful for blood sugar regulation and Damiano says he notices “profound” drops in his blood sugar while on walks in the woods with his wife. “If you have a meal and blood sugar rises, take a walk, it’s like magic,” he says. “It can reinforce people to think about exercise after meals.”
However, experts admit there’s no research showing wearing a CGM can improve a person without diabetes’ health. So far all evidence is anecdotal. Though it’s unlikely the devices would cause any major safety problems beyond possible rashes or infections at the injection site, that hasn’t been studied in people without diabetes either. UVA’s Kovatchev also argues that CGMs could be more helpful for people without diabetes with some fine-tuning. “There’s a need for some analytics that could process the data appropriately and provide [actionable] information to people versus a datastream every five minutes,” he says.
That reality may not be so far off. As Gizmodo reported in February, the company Sano Intelligence is planning to release a CGM for the general public. The device may be released in beta later this year.
Firchau says he believes monitoring blood sugar via CGM will likely become common practice. “It motivates you,” he says. “I see a future where this is an incredible tool to empower people to take control of what goes into their mouth.” Until then, it remains a helpful device for people with chronic disease, and a plaything for personal data enthusiasts.