I’m an RD, and Here’s Why I Don’t Recommend Wearing a Continuous Glucose Monitor if You Don’t Have Diabetes

One type of wearable tech gaining significant attention in the health and fitness community is the continuous glucose monitor (CGM). While traditionally intended for people with insulin-dependent diabetes, people without diabetes are starting to use these devices to "hack" their blood sugars.

But is using a CGM if you don't have diabetes worth your time and money? The answer might surprise you.

What is a continuous glucose monitor?

A CGM is a wearable device that continuously tracks glucose levels without the need for traditional fingerstick tests. Unlike the fingerstick method, which tests blood glucose (aka blood sugar), a CGM checks glucose levels in the interstitial fluid (the fluid found between cells). A tiny sensor inserted under the skin measures your glucose levels, and a wireless transmitter sends the results to your cell phone or a wearable device. Pretty cool, right?

The sensor in a CGM tests glucose levels every few minutes, whether you're resting, exercising, working, or sleeping. Some other features you may see on a CGM include:

• An alarm that goes off when your glucose levels are too low or too high
• A system that allows you to track meals, physical activity, and medications
• The ability to download your data to a computer or smartphone to see your glucose trends
• Pairing with insulin pumps so that the pump will automatically adjust insulin dosing to glucose levels

To ensure your CGM is calibrated correctly, it's important to test a drop of blood on a standard glucose meter. The reading should be similar on both devices.

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What are the health benefits of using a continuous glucose monitor if you're living with diabetes?

For people with type 1 diabetes (or type 2 diabetes who require insulin), the information collected from continuous blood glucose monitoring is an indispensable part of their diabetes care plan.

Tracking glucose levels gives you information about how much insulin your body needs and when it needs that insulin. This allows for better blood glucose management and fewer "glycemic excursions" (i.e., having blood glucose levels that are out of your personalized target). Keeping blood glucose within a person's individualized target range can help prevent diabetes complications in the short- and long-term and improve a diabetic person's overall health and quality of life.

There may also be some benefits to using a CGM for people diagnosed with prediabetes or with a higher risk of developing diabetes due to family history or other health factors, says Lauren Kelley-Chew, MD and Head of Clinical Products at Levels. She notes that more than one in three Americans live with prediabetes, and over 80 percent of this population is are unaware that they have it. Kelley-Chew explains that insulin resistance can occur for many years before advancing to prediabetes, and that it's influenced by various lifestyle factors, including diet, exercise, sleep quality, and stress levels.

Using a CGM can give you a fuller picture of your metabolic health and insulin resistance. This is important because the earlier a person understands their metabolic health, the sooner they can make changes to prevent or reverse that dysfunction before it develops into type 2 diabetes.

What are the health benefits of using a continuous glucose monitor when you don't have diabetes?

For people without prediabetes or diabetes, the benefits of using a CGM are less clear. A study of 153 people who didn't have diabetes showed that blood sugar levels were normal or nearly normal about 96 percent of the time. Is it worth measuring something if it's only out of target four percent of the time? Many people would argue that it isn't.

Another very small study of just 19 people showed that people who wore a CGM reported being more motivated to exercise. While this is a positive effect, wearing a different fitness device would likely provide similar motivation.

Overall, there are currently no studies in peer-reviewed medical journals demonstrating that using a CGM when you don't have diabetes is beneficial. It's also important to note that wearing a CGM is not a benign practice. There are some pitfalls to consider before jumping on the CGM bandwagon.

For people with diabetes, CGMs aren't a fun toy they can choose not to use if they don't feel like it. They're an incredibly useful, disturbingly expensive medical device that many people who have diabetes can't even afford to access.

Pitfalls of using a continuous glucose monitor when you don't have diabetes

While it may seem relatively harmless, wearing a CGM when you don't have diabetes can have some drawbacks. As Melissa Mitri, MS, RD, of Melissa Mitri Nutrition explains, wearing a CGM could make a person unnecessarily anxious about their glucose numbers. This could be particularly harmful to a person with a history of disordered eating, food restriction, or even anxiety in general. Diet culture is rampant in our society, and obsessively tracking our body and fitness metrics can certainly feed into that.

In fact, a study of 647 first-year university students examined whether wearing technology-based weight-related self-monitoring devices was associated with eating disorder behaviors. They found that the students who wore fitness technology were more likely to report eating disorder behaviors like fasting, skipping meals, and excessively exercising. While no studies have looked at the effects of CGMs on disordered eating behaviors, they could promote an unhealthy obsession with having glucose levels within a very tight target.

Misguided nutrition advice is often handed out alongside CGMs. In particular, there may be an encouragement to restrict carbohydrates. For most people (including people with diabetes), extreme carbohydrate restriction is unnecessary, and it can even become extremely unhealthy. If someone does choose to use a CGM, they should work with a registered dietitian to ensure that they include carbohydrates in a way that is compatible with their individual metabolism.

Aside from the potential for developing an obsession with glucose levels, there are practical considerations when using a CGM. As Colleen Kiley, RD, a registered dietitian and certified diabetes care and education specialist notes, a potential drawback of wearing a CGM when you don't have diabetes is getting a lot of low glucose alerts, especially during the night.

Kiley explains that sensors will alarm at a glucose reading of 70 mg/dL or lower. This glucose level can be normal for a person who doesn't have diabetes and isn't on any medications that cause low blood glucose. The sensor can also alarm if you put pressure on it, such as when you're sleeping. These alarms can be loud and disruptive to a person's sleep. (Ask any diabetic about sleep loss due to their condition, and they'll have plenty to say on the matter.)

Access to continuous glucose monitors is an issue

In addition to the potential for developing an obsession with achieving "perfect" glucose reading, there are potential ethical issues with people without diabetes using CGMs.

Why is it an ethical issue? CGMs are lifesaving technology that many people with diabetes can't afford. CGM devices are often expensive and aren't always covered by insurance. Plus, the sensors need to be replaced every seven to ten days, a cost that can add up quickly.

According to the American Diabetes Association, lack of access to CGMs disproportionately affects people that have a lower income, are elderly, and/or are people of color compared to others with diabetes. We also know that lower socioeconomic status is associated with an increased risk of type 2 diabetes. In other words, the people who most need access to CGMs often can't afford them.

Final thoughts

The idea that we need to know the minutiae of our biological processes feeds into diet culture. When you dig into the (lack of) research, promoting CGMs to healthy people feels like trying to get people to worry about something they don't need to be worried about to sell them something they don't need. It's fear-mongering at its best.

For people with type 1 and type 2 diabetes who depend on CGMs for their livelihood, the "trend" of using a CGM without diabetes can feel like a huge slap in the face. After all, for people with diabetes, CGMs aren't a fun toy they can choose not to use if they don't feel like it. They're an incredibly useful, disturbingly expensive medical device that many people who have diabetes can't even afford to access.

If you have a family history of diabetes or have been diagnosed with prediabetes, a CGM can be a valuable tool to help prevent the development of diabetes. But for the average, healthy person, there is little evidence that using a CGM has any health benefits. CGMs are just the latest in health fads, and until we learn more about how they work in healthy people, they're likely not worth your time or money.