People who are interested in tracking their health and fitness can find a tremendous variety of wearable devices to suit their needs. Interested in monitoring your health? There are devices that track heart rate, respiratory rate, blood pressure and even blood oxygen levels and the electrical activity of your heart. Curious about your fitness metrics? Choose a wearable that tracks steps taken, calories burned, distance traveled and recovery metrics. Want to crunch the numbers on your lifestyle choices? Track stress levels, hydration, sleep quality and mindfulness.

A relative newcomer to this party is continuous glucose monitoring. You may have clients asking about this topic, as it’s been trending on social media in recent months. While it’s outside the scope of practice of ACE Certified Professionals to diagnose prediabetes or diabetes (or any other condition), it’s essential that you stay informed on popular health- and fitness-related topics that may be of interest to your clients. After all, it’s well within your scope to provide evidence-based resources to your clients so they can make informed decisions about their health.

The first continuous glucose monitor (CGM), which was approved by the U.S. Food and Drug Administration (FDA) in 1999, collected glucose data for three days, which could then be reviewed by the patient’s healthcare provider. As you might imagine, the technology has improved dramatically since then.

Modern CGMs involve wearing a small sensor, usually on the back of the upper arm, that streams glucose readings directly to a phone app. To be specific, a CGM measures glucose levels in the interstitial fluid that surrounds cells outside of the blood vessels, rather than in the blood itself (more on this below). This data allows users to gain insights into trends and fluctuations throughout the day.

This type of information is obviously valuable for individuals with diabetes or prediabetes, but what is the value of tracking spikes and dips in glucose levels for people who do not have these conditions? Perhaps a client is battling fatigue and wondering if their glucose levels may be to blame, or maybe they’re simply a health fanatic who loves to have as much insight into their health and wellness as possible.

Regardless of why a particular client may be interested in using a CGM, there are some key questions that should be considered. Note that for the purposes of this article we are primarily focused on CGM use among individuals who do not have diabetes, prediabetes or any other condition for which a physician may prescribe the use of the device.

What kind of data does a CGM provide and how accurate is that data?

As described above, a CGM provides readings by measuring glucose levels in the interstitial fluid (rather than in the blood) 24 hours a day, providing insights into trends and fluctuations. However, there can be a 5- to 20-minute lag, meaning that the data isn’t truly delivered in “real time.” As Rachele Pojednic, PhD, EdM, FACSM, lecturer (adjunct) at Stanford University and director of scientific research at RestoreLab, explains, “Since CGMs measure glucose in interstitial fluid, there’s a lag compared to blood glucose, and readings can be influenced by hydration, sensor placement and other factors.” This can cause discrepancies during rapid glucose fluctuations.

Dominique Adair, MS, RD, clinical director at Knownwell Health and ACE Scientific Advisory Panel member, explains that most CGMs provide glucose readings within approximately 10% of the actual blood glucose value. This level of precision makes CGMs reliable for tracking glucose trends and informing diabetes management decisions. 

However, CGMs have been shown to have a significant margin of error, particularly for people without diabetes. Dr. Pojednic says that for individuals with diabetes who need to manage significant glucose variability, this margin of error is acceptable, but for those with normal glucose regulation, small variations may not be clinically relevant, and CGM readings could lead to unnecessary concern over normal physiological responses (more on this below).

How useful is the data provided by CGMs for people who do not have diabetes?

CGMs have been shown to improve blood sugar control in people with diabetes, explains Adair, but their benefits for other groups, like those with prediabetes, are less well studied. “Research suggests that using a CGM may help individuals in the early stages of dysglycemia [i.e., abnormal blood sugars] recognize how food and activity affect their blood sugar. However, evidence is mixed on whether CGM use directly reduces the progression from prediabetes to diabetes. Additionally, CGMs are increasingly being used for metabolic disease management (i.e., for people who have obesity), performance nutrition and other applications, but further research is needed to determine their efficacy and return on investment.”

Pojednic summarizes it this way: “While this data is critical for individuals with diabetes to manage their blood sugar, its utility for those without diabetes is less clear. Many people without diabetes already maintain glucose levels within a normal range and small fluctuations in response to food, exercise or stress are completely normal.”

In other words, increases and decreases in blood glucose levels are to be expected over the course of the day and may not be cause for concern, which brings us to a couple of important follow-up questions…

Can a CGM help clients identify specific foods or habits that cause blood sugar spikes or drops? And what can health coaches and exercise professionals and their clients do with that information?

The core question in this entire conversation is whether the data gathered by a CGM can be used to modify behavior in a way that positively impacts a client’s overall health. Data is great and can be fun and educational for some users, but does it lead to a practical application? We asked our experts to weigh in on these questions.

“If someone is going to use a CGM, one of the most useful aspects of the data is the ability to see how specific foods, meal compositions and meal timing impact individual glucose levels,” explains Dr. Pojednic. “Clients can experiment with different carb sources, fiber intake or meal order (e.g., protein before carbs) to learn more about their body. Exercise professionals can also use this data to help clients optimize workout timing—showing how different types of exercise (strength training vs. cardio) impact glucose and how fueling strategies can be adjusted for performance and recovery.”

Adair agrees with this approach. “CGMs can help clients identify specific foods or habits that cause blood sugar spikes or drops by providing data on how their body responds to meals, snacks and lifestyle factors like stress and sleep. By tracking patterns, clients can gain insights into which foods lead to sharp increases in blood sugar and which promote more stable levels.

“Exercise professionals and their clients can use this information to optimize meal timing around workouts; encourage balanced meals with protein, fiber and healthy fats to reduce glucose spikes; adjust pre- and post-workout nutrition to sustain endurance; identify patterns of low energy or cravings linked to blood sugar fluctuations; and support sustainable behavior changes.”

Pojednic says that health coaches and exercise professionals should seek education on how to interpret data on “spikes” in glucose, which are not useful or actionable without context. “A glucose ‘spike’ after eating isn’t inherently bad—postprandial rises in glucose are expected and part of normal metabolism,” she explains. “There’s little evidence that reducing these transient spikes in healthy individuals improves long-term health outcomes. While exercise pros and clients might experiment with timing or meal composition, the benefits of this level of precision remain questionable.”

Adair agrees that CGMs offer valuable insights but says that health coaches and exercise professionals should encourage clients to interpret the data in collaboration with a healthcare provider, such as a registered dietitian nutritionist or physician, to ensure a balanced and evidence-based approach to nutrition and exercise.  

What lifestyle or dietary changes can be made based on CGM data to optimize blood sugar levels? And what, besides food, impacts blood sugar?

According to Dr. Pojednic, the most effective ways to support glucose regulation—regular physical activity, high-fiber and protein-rich meals, quality sleep and stress management—are already well-established without the need for CGM data. “People without diabetes likely don’t need a CGM to tell them that a good night’s sleep, regular movement and balanced meals are beneficial,” she says.

That said, real-time CGM use may lead to behavioral modifications in food selection and physical activity. Unfortunately, there is limited data on the effectiveness of CGM use in facilitating lifestyle changes. “As with many tools,” says Adair, “the impact will depend both on the user and how engaged they are.”

Are there any specific populations or individuals who might benefit more from using a CGM, even if they don’t have diabetes or prediabetes?

A CGM can help someone understand their own body and potentially give insight into early indications of insulin resistance or metabolic dysfunction. It can also help clients better understand which foods actually impact blood glucose and which don't.

According to Adair, outside of individuals with diabetes, probably the most promising data is in people with prediabetes, in terms of helping them monitor glycemic response to lifestyle behaviors and then modify habits to produce normoglycemia. “Beyond that application,” she says, “the literature in CGM use as an intervention in metabolic disease/obesity is interesting and promising. For healthy people, there is a variance in blood glucose response to foods; things like genetics, gut microbiota composition, meal composition and other lifestyle factors (sleep, stress and illness) contribute to how blood glucose response differs from person to person.”

Finally, are there any risks involved with the use of a CGM?

Adair explains that there is growing concern among clinicians who work with people who have clinical and subclinical eating disorders that CGMs may trigger unhealthy behaviors. Vulnerable individuals using CGMs may develop unhealthy monitoring habits, leading to increased anxiety about normal glucose fluctuations and potentially fostering disordered eating patterns.

If you have a client who tends to become obsessed with the numbers (rather than looking at the overall picture), whether their focus is steps taken, calories burned, ounces of water consumed or any other variable, the addition of yet another number to track may not be optimal.

Another concern is cost. These devices can be expensive, and the benefits may not justify the investment for most people who do not have diabetes. As Adair explains, the high cost of CGMs raises concerns about accessibility and equity in metabolic health management. “While these devices provide valuable insights,” she says, “a suggestion of their widespread use for people who have obesity could create even more of a divide between those who can afford them and those who cannot. Instead of relying on CGMs as a primary tool, a more inclusive approach would focus on evidence-based, sustainable lifestyle strategies that are accessible to all.”

Adair adds that CGMs should not be used to demonize foods, as a healthy body naturally maintains glycemic control without intervention. “For people without diabetes, a CGM is not necessary to eat well, and an overemphasis on glucose data rather than balanced food choices can be counterproductive, potentially doing more harm than good.”

Final Thoughts

“Some companies promote CGMs as a tool for ‘optimizing health,’ but there’s little evidence that tracking glucose in real time leads to better health outcomes in people without diabetes,” explains Dr. Pojednic. “Glucose regulation is important, but focusing too much on moment-to-moment fluctuations might distract from more meaningful, evidence-based lifestyle behaviors.”

“If someone is already engaging in regular exercise, eating a balanced diet and getting quality sleep,” Dr. Pojednic continues, “using a CGM likely won’t offer much additional benefit. However, if they are not (and let's be honest, most people are not properly engaging in these lifestyle behaviors), it can be a good education tool to understand metabolism and how fueling and training affect your body.”

To sum up, continuous glucose monitoring provides reliable, meaningful data but it may not be as useful for clients who do not have diabetes or prediabetes. Glucose is an important health marker, but it is one small piece of an exceedingly complex puzzle. It’s important that you are prepared to discuss CGMs with inquiring clients—and evidence-based and balanced resources like this article should be part of that conversation—but it’s more important that you teach your clients how to achieve a balanced lifestyle that includes exercise, healthy eating, stress management and all the other elements of overall health. If they consistently do those things well, glucose monitoring is likely not required.