Is a CGM worth it if you don’t have diabetes? What the evidence shows

What the FDA cleared, and for whom

For prediabetes or obesity, a 2026 review calls the evidence for CGM limited and indirect⁹. A meta-analysis of mostly diabetes trials found a modest drop in HbA1c with CGM feedback, but no clear effect on weight⁶. The sections below also cover what normal glucose looks like in healthy people, and the risks of reading too much into normal ups and downs.

In March 2024 the FDA cleared Dexcom’s Stelo Glucose Biosensor System as the first over-the-counter CGM, for adults 18 and older who don’t use insulin¹. In June 2026 it widened that clearance to anyone 2 or older who doesn’t use insulin, with an adult caregiver supervising children¹¹. That includes people with diabetes who take oral medicines, and people without diabetes who want to see how diet and exercise affect their blood sugar^{1, 11}. It isn’t intended for people with problematic hypoglycemia (dangerously low blood sugar), because it isn’t designed to alert you to it^{1, 11}. Each sensor can be worn for up to 15 days, and the app shows glucose readings and trends every 15 minutes¹.

In June 2024 Abbott announced FDA clearance for two more over-the-counter systems². Abbott describes Lingo as being for consumers 18 and older who aren’t on insulin and want to improve their overall health and wellness². It isn’t intended for diagnosing diseases, including diabetes². Libre Rio is for adults with type 2 diabetes who don’t use insulin². The Lingo sensor is worn on the upper arm for 14 days, but Abbott’s own footnote says 77.1% of sensors lasted the full 14 days².

Clearance means the FDA allowed the device to be sold for its stated use. The FDA said a clinical study found Stelo performed similarly to other integrated CGMs¹. That study tested how the device performed, not whether wearing it improves health outcomes in people without diabetes¹. The FDA also told users not to make medical decisions based on the readings without talking to a health care provider¹.

What normal glucose looks like in healthy people

Reference data for modern sensors come from a 2019 study at 12 US centers⁴. In it, 153 healthy, non-pregnant, non-obese participants aged 7 to 80 wore a blinded Dexcom G6 sensor for up to 10 days⁴. The authors presented the results as benchmark values for future research⁴. They also noted that 93% of participants were white, so they couldn’t check whether the values hold across races⁴.

Mean glucose was 98 to 99 mg/dL in every age group except those over 60, whose mean was 104 mg/dL⁴. Participants spent a median 96% of the day between 70 and 140 mg/dL⁴. Time above 140 mg/dL was a median 2.1% of the day, about 30 minutes⁴. Time below 70 mg/dL was a median 1.1%, about 15 minutes⁴.

In other words, short rises above 140 mg/dL and brief dips below 70 mg/dL both showed up in this healthy reference group. A 2024 narrative review looked at CGM use in people not living with diabetes⁷. It cited one study in this group in which participants spent 97% of the day between 70 and 180 mg/dL⁷. The same study found a coefficient of variation of 20%, below the 36% variability threshold used in diabetes care⁷. But the review questioned whether that threshold applies to people without diabetes⁷.

The review also said clinical benchmarks and scoring methods for CGM measures in people without diabetes are significantly under-researched⁷. Until prospective studies define thresholds, it advised against using CGMs to screen for or stratify type 2 diabetes risk in this group⁷.

How accurate are over-the-counter CGMs?

CGMs measure glucose in the fluid under the skin, not in blood. The FDA’s accuracy standard for integrated CGMs, the category Stelo was cleared under, is set in blood-glucose terms^{1, 10}. Across the whole measuring range, the share of readings within 20% of blood glucose must exceed 87%¹⁰.

In the 70 to 180 mg/dL range, the lower 95% confidence bound for the share of readings within 15% of blood glucose must exceed 70%¹⁰. That’s the range almost all readings fell in during the healthy reference study above⁴. On a blood value of 140 mg/dL, a 15% error is 21 mg/dL either way. So the standard leaves room for readings that land on the wrong side of 140 mg/dL, the upper cutoff used in that reference study⁴.

Accuracy has been studied less in people without diabetes. The 2024 narrative review found that accuracy studies in this group were small and unrepresentative, often lacked confidence intervals and mostly used older devices⁷. One study reported lower overall FreeStyle Libre accuracy in people without diabetes, and others linked higher body fat and BMI with lower sensor precision⁷. Studies in people with and without diabetes reported larger bias during physical activity⁷. The review also noted that no human trial has yet tested the idea that under-skin and blood glucose track more closely in people without diabetes⁷.

Repeatability is a second problem. In an NIH analysis of two inpatient feeding studies, adults aged 18 to 50 without diabetes ate the same meals twice, about a week apart, while wearing CGMs⁵. Their glucose responses to identical meals correlated only weakly to moderately: r = 0.47 for an Abbott sensor in 14 participants, and r = 0.43 for a Dexcom sensor in 30⁵. Intraclass correlations of 0.31 and 0.14 indicated poor reliability⁵.

The authors concluded that individual responses to duplicate meals were unreliable in adults without diabetes⁵. The version reviewed here is a preprint that hadn’t been peer reviewed when posted⁵. It also used older sensors (FreeStyle Libre Pro and Dexcom G4 Platinum)⁵.

The practical point is that one spike after one meal is a noisy signal. Ranking foods as good or bad from a single reading, or from two readings that disagree, can mislead.

What the evidence shows: modest effects, mostly in diabetes

The broadest test of CGMs as a behavior-change tool is a 2024 meta-analysis of 25 randomized trials with 2,996 adults⁶. Most trials (17) enrolled people with type 2 diabetes, and only 3 enrolled people with overweight or obesity⁶. Every intervention combined CGM feedback with other components, such as CGM-based guidance or tracking of behavior⁶.

Compared with control groups, these combined interventions lowered HbA1c by 0.28 percentage points (95% CI 0.15 to 0.42; 23 trials)⁶. They also increased time in range by 7.4 percentage points (95% CI 2.0 to 12.8; 10 trials)⁶. The effect on weight was small and not statistically significant (-0.7 kg, 95% CI -1.4 to 0.0; 8 trials)⁶. So was the effect on BMI (-0.4, 95% CI -0.9 to 0.0; 9 trials)⁶. Diet and physical activity couldn’t be pooled⁶.

The certainty is limited. Heterogeneity for HbA1c was high (I² 88%)⁶. The planned subgroup analysis by diabetes status wasn’t reported because there were too few trials⁶. The review also didn’t report a formal certainty-of-evidence rating⁶. Of the 25 trials, 11 reported conflicts of interest with CGM-affiliated companies⁶.

The authors described the effects as favorable but modest and called for more research in people without diabetes⁶. A 2026 review in JAMA Internal Medicine drew on systematic reviews, meta-analyses of randomized trials and guidelines⁹. In adults with type 2 diabetes, it likewise found a modest but consistent HbA1c reduction of about 0.3% compared with finger-stick monitoring or usual care⁹. For type 2 diabetes without glucose-lowering therapy, prediabetes or obesity, it found only limited and indirect evidence for CGM⁹.

The 2024 narrative review looked at three claimed uses in people without diabetes: detecting abnormal glucose, changing behavior and improving metabolic health⁷. It found a lack of consistent, high-quality evidence for all three⁷. The personalized-nutrition studies it discussed tested CGMs alongside diet programs, so the sensor’s own contribution was hard to isolate⁷. Some were also industry-sponsored⁷.

A CGM may help some people see how meals and activity line up with their glucose. But the trials so far don’t show that this feedback alone improves health in people without diabetes.

What the evidence does not show

We found no randomized trial showing that over-the-counter CGM use by healthy adults lowers the risk of type 2 diabetes, heart disease or death. The 2026 JAMA Internal Medicine review concluded that CGM should be used in response to a specific patient problem, not as a default⁹. It also said overuse should be avoided where benefit is unproven⁹. In the University of Gothenburg’s summary of that review, the researchers said they found no evidence that CGM improves health or prevents disease in people without diabetes⁸.

The 2024 narrative review likewise concluded that studies in people without diabetes lack assessments of long-term benefit and haven’t shown clinically significant effects on health outcomes⁷. In their present form, it said, CGMs appear not appropriate for optimizing metabolic health or preventing metabolic conditions⁷. It also noted that clinical guidelines don’t recommend CGMs outside type 1 diabetes or insulin-treated type 2 diabetes⁷.

The evidence also doesn’t show that flattening normal after-meal rises improves health in people whose glucose is already in the normal range⁷. Nor does it show that food scores built from a few meal responses are reliable^{5, 7}. In the PREDICT 1 study discussed in the 2024 review, meal glucose responses were less informative than fasting glucose for predicting a 10-year cardiovascular risk score⁷. Adding them improved that prediction only slightly, with the area under the curve rising from 0.69 to 0.72⁷.

Safety and risks

The physical risks are mostly at the sensor site. In the clinical study submitted for Stelo, reported adverse events included local infection, skin irritation and pain or discomfort¹. The over-the-counter systems covered here are cleared only for people who don’t use insulin^{2, 11}. Stelo isn’t intended for people with problematic hypoglycemia, because it doesn’t alert users to dangerously low glucose¹. The FDA’s notice of Abbott’s late-2025 sensor recall named certain FreeStyle Libre 3 and FreeStyle Libre 3 Plus sensors, not Lingo¹².

For healthy users, the bigger concern is how the numbers are read. The 2024 narrative review found that studies of the psychological effects of commercial CGM use are lacking⁷. It flagged possible effects on eating habits as an under-researched area, and warned that inaccurate low readings could cause unwarranted anxiety⁷. It also noted that research on calorie and fitness tracking links that kind of monitoring with anxiety, compulsive behavior and disordered eating⁷. But CGM-specific effects haven’t been studied⁷.

In a University of Gothenburg news release, the authors of the 2026 JAMA Internal Medicine review warned that normal glucose fluctuations can easily be overinterpreted⁸. That may lead to unnecessary and unhealthy dietary restrictions or anxiety, they said⁸. They added that healthy people are already seeking medical care to interpret their readings⁸.

A separate risk is devices that aren’t CGMs at all. In February 2024 the FDA warned people not to buy or use smartwatches or smart rings that claim to measure blood glucose without piercing the skin³. It said it hasn’t authorized any such device, and that inaccurate readings could lead to dosing errors with glucose-lowering medicines³. The warning doesn’t cover watch apps that display data from FDA-authorized CGMs³.

What to look for before you buy a CGM

If you don’t have a diabetes diagnosis, the evidence above supports treating a CGM as a way to observe glucose patterns, with known limits, rather than as a health intervention. These checks follow from that evidence.

• An FDA clearance for over-the-counter use that covers you: Lingo is for adults 18 and older not on insulin, and Stelo for anyone 2 or older not on insulin and without problematic hypoglycemia^{1, 2, 11}
• No needle-free watch or ring that claims to read blood glucose, since the FDA hasn’t authorized any³
• Realistic expectations about normal readings: in healthy people, glucose spent a median of about 30 minutes a day above 140 mg/dL⁴
• Room for error in the readings: between 70 and 180 mg/dL, the FDA’s accuracy standard for integrated CGMs requires only that the lower confidence bound for the share within 15% of blood glucose exceed 70%¹⁰
• Skepticism about food scores or metabolic-health claims built on single-meal readings, which repeated poorly in adults without diabetes^{5, 7}
• The recurring cost: sensors are worn for up to 14 to 15 days, so year-round use means about two sensors a month^{1, 2}
• The chance a sensor ends early: in Abbott’s own study, 77.1% of Lingo sensors lasted the full 14 days²
• Attention to how tracking affects you: anxiety about food or cutting out foods is a concern researchers have raised but haven’t yet studied directly^{7, 8}
• The FDA’s advice: don’t make medical decisions from the readings without talking to a health care provider¹

Sources

1. FDA Clears First Over-the-Counter Continuous Glucose Monitor US Food and Drug Administration, 2024 · regulator
2. Abbott Receives U.S. FDA Clearance for Two New Over-the-Counter Continuous Glucose Monitoring Systems Abbott, 2024 · manufacturer
3. Do Not Use Smartwatches or Smart Rings to Measure Blood Glucose Levels: FDA Safety Communication US Food and Drug Administration, 2024 · regulator
4. Continuous Glucose Monitoring Profiles in Healthy Nondiabetic Participants: A Multicenter Prospective Study The Journal of Clinical Endocrinology & Metabolism (Shah et al.), 2019
5. Imprecision nutrition? Duplicate meals result in unreliable individual glycemic responses measured by continuous glucose monitors across four dietary patterns in adults without diabetes medRxiv preprint (Hengist et al., NIDDK), 2023
6. The efficacy of using continuous glucose monitoring as a behaviour change tool in populations with and without diabetes: a systematic review and meta-analysis of randomised controlled trials International Journal of Behavioral Nutrition and Physical Activity (Richardson et al.), 2024 · meta-analysis
7. Innovative solution or cause for concern? The use of continuous glucose monitors in people not living with diabetes: A narrative review Diabetic Medicine (Oganesova, Pemberton and Brown), 2024
8. No evidence that continuous glucose monitors improve health in people without diabetes University of Gothenburg, 2026 · news
9. Continuous Glucose Monitoring in Type 2 Diabetes and Beyond: A Review JAMA Internal Medicine (Dower, Johansson, Camp, Montori and Lipska), 2026
10. 21 CFR 862.1355: Integrated continuous glucose monitoring system Electronic Code of Federal Regulations (FDA regulation, 21 CFR Part 862) · regulator
11. FDA Clears First Over-the-Counter Continuous Glucose Monitor for Children US Food and Drug Administration, 2026 · regulator
12. Glucose Monitor Sensor Recall: Abbott Diabetes Care Removes Certain FreeStyle Libre 3 and FreeStyle Libre 3 Plus Sensors US Food and Drug Administration, 2026 · regulator