Almost 2.4 million Americans wear continuous glucose monitors, or CGMs, to track their blood sugar—and not all of them have diabetes. More and more healthy people are wearing them to understand how food, exercise, and other factors impact blood sugar levels—and, by extension, the rest of their bodies. But are they worth the cost, or just another trendy health gadget? Hone Health investigates.

A randomized controlled trial published recently in The American Journal of Clinical Nutrition found that blood sugar responses to the same meal may vary in an individual. In theory, this means the devices may not be very effective at helping us figure out what foods cause our glucose levels to spike, at least not consistently.

However, some experts disagree and think continuous glucose monitors can offer useful information, even to non-diabetics. So who are they good for, and what good can come from using them?

If You Don't Have Diabetes, Should You Monitor Your Blood Sugar?

You don't need to monitor your blood sugar unless you're at an increased risk of developing prediabetes or diabetes. Most non-diabetics do so because they want to.

"For patients who are trying to lose weight, seeing what's happening in their body in real-time based on the food that they're eating can be beneficial to make better choices in the future," says Ari Eckman, M.D., an endocrinologist and expert in diabetes and metabolism.

Spikes in blood sugar after eating (called postprandial spikes) are normal, but frequent, super-high spikes can cause oxidative stress and increase inflammation, which can lead to a host of health issues.

Glucose spikes can also weaken blood vessels, cause plaque in the arteries, and increase insulin resistance and the risk of developing diabetes.

Big drops in blood sugar following a spike can trigger hunger, overeating, and weight gain.

What Are the Benefits of Monitoring Blood Sugar?

For people without diabetes, the goal is to gather data, identify patterns, and make changes to your diet, exercise, and other lifestyle factors.

Glucose levels can fluctuate daily and spike for various reasons, not just following a carb-heavy meal. Inadequate hydration, certain medications, stress (including healthy stress on the body from exercise), illness, and hormonal fluctuations can all affect glucose levels.

Reveals impact of diet on blood sugar

CGMs can show minute-by-minute what happens to your blood sugar after you eat or drink something.

"I'm pretty trim, but I've gone from 210 pounds to 197 pounds in a month," says Bob Arnot, M.D. The former chief medical correspondent for NBC News doesn't have diabetes but has worn a CGM for the past year. "The most fun is seeing how particular foods wreck your blood sugar readings. Mine was a turkey sandwich with stuffing. My glucose was through the stratosphere."

Shows how exercise modulates blood sugar

Aerobic exercise typically leads to a more gradual decline in blood sugar levels, as muscles pull glucose from the blood for fuel.

However, HIIT, heavy lifting, or other strenuous forms of exercise cause the body to release stress hormones, which stimulate glucose production. A CGM can show users when these spikes occur during and after workouts.

More research is needed into how CGMs can provide exercise-related data to wearers who don't have diabetes.

One study found that CGMs may help athletes monitor whether they're fueling adequately, how best they can optimize their carb intake, and how to prevent energy crashes during training and competitions.

Do You Need a Prescription for a Continuous Glucose Monitor?

Most CGMs require a prescription. However, the FDA recently cleared the first over-the-counter CGM for purchase without a prescription, the Dexcom Stelo.

If you get one, Eckman says you should expect to spend about $50 to $150 on sensors every two weeks. The Dexcom Stelo costs $99 for a one-time purchase of two sensors, $89 for a monthly subscription, and $252 for a three-month supply.

Eckman says some insurance plans may cover a CGM if you don't have diabetes, and notes that they're eligible for FSA/HSA coverage.

How Does a CGM Work?

A CGM has a small sensor that's inserted underneath the skin and secured with adhesive to your arm or stomach. A transmitter sends the collected data to a smartphone app or another receiver.

People with diabetes set alarms to let you know when your blood sugar levels are too high or too low, but non-diabetics likely won't need to do that, Eckman says.

CGMs measure glucose in the interstitial fluid, which surrounds the cells in your body. CGMs show the direction and rate of change of your glucose levels and calculate the percentage of time they stay within a target range.

Drawbacks to Monitoring Your Blood Sugar

"A CGM is just a tool," Arnot says. "It won't magically fix your diet or health. It requires effort, self-reflection, and a willingness to make changes."

Sometimes, there can be such a thing as too much information—and the research isn't totally conclusive yet. Research into the efficacy and reliability of CGMs is largely centered on the diabetic population, not on people who don't have diabetes.

Data is difficult to interpret

As a doctor, Arnot understands what all of the numbers his CGM gathers mean. Experts recommend that non-diabetics who use a CGM work with their physician to better understand the information being collected and then figure out what to do with it.

Some research has found CGMs regularly find different blood sugar reactions to the same foods meal-to-meal, even within the same person. Plus, glucose levels can fluctuate from day to day for reasons other than food and exercise.

"Without proper guidance, people might misinterpret normal glucose fluctuations, leading to unnecessary anxiety or unhealthy dietary restrictions," Arnot says.

Do continuous glucose monitors support hypoglycemia?

Some research has indicated that, in theory, a CGM could help people with hypoglycemia detect when their levels drop too low. Still, manufacturer websites state clearly their sensors have not been designed for and should not be used by people at risk for or who have hypoglycemia.