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Continuous Glucose Monitors in People Without Diabetes

What continuous glucose monitors measure in people without diabetes, what regulators say, how accurate they are, and what trials show about using them for diet and longevity goals.

Content last updated October 22, 2026. This page has not been medically reviewed.

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What this page covers

A continuous glucose monitor (CGM) is a small sensor worn on the skin that reads sugar in the fluid under the skin every few minutes and sends the numbers to a phone. They were built for people with diabetes. Some people without diabetes now wear them hoping to learn about diet, metabolism and healthy aging. This page explains what the research shows. It is information only and does not tell anyone what to eat, which numbers to aim for or whether to buy a device. For a practical view of the wider tracking trend, see Nutrition Tracking and Continuous Glucose Monitors for People Without Diabetes.

Evidence labels used: approved device (cleared by a regulator, for a stated use), promising but limited, mixed, insufficient evidence, marketing claim.

What is normal for people without diabetes?

There is no single agreed "normal" pattern. In a reference study of 60 people without diabetes or prediabetes who passed a normal glucose tolerance test (average age 43), the median time spent below 70 mg/dL (3.9 mmol/L) was 1.6% and the mean 3.2%, so brief low readings were common in healthy people. [3] This is one reason an alert about a reading does not by itself mean something is wrong. See Interpreting Test Results Without Overinterpreting.

How accurate are the readings?

In 34 healthy adults (average age about 66), a sensor compared with blood drawn from a vein over 24 hours had an average error of 17.6%, and most measures of glucose swings were lower on the sensor than in blood. [4] That 2015 study used an older sensor, so newer devices may differ, but it shows that accuracy in people with normal glucose is not guaranteed.

Do glucose readings change health outcomes?

Different people, different responses. An 800-person study that tracked glucose for a week and 46,898 meals found high variability in responses to identical meals. [5] That finding describes variation; by itself it is not proof that acting on it improves long-term health.
Behavior-change trials. A 2024 review of 25 randomized trials (2,996 people) found favourable but modest improvements in blood sugar control with CGM feedback, but most trials were in people with diabetes (17 of 25 in type 2 diabetes), and effects on weight and BMI were not statistically significant. [6] In that review 11 of 25 trials reported links to CGM makers. [6]
Healthy adults. A 2025 systematic review focused on people without diabetes concluded that data are scarce and the effect on cardiovascular outcomes is unclear. [7]

Label: insufficient evidence that routine CGM use in healthy people extends life or prevents age-related disease; promising but limited as a feedback tool for some people with metabolic conditions, under clinical care.

Possible downsides

Sensors can irritate skin or cause infection. [1] The sources read here did not measure worry, anxiety or eating behavior in people without diabetes, so those possible downsides are not quantified.

How to evaluate claims

Is the claim about a measured glucose value or about a health outcome like lifespan?
Was the study done in people like you (age, health, no diabetes)?
Who funded it?
Does the device have regulator clearance for the use being advertised?

Frequently asked questions

Can I wear a glucose monitor if I do not have diabetes?

In the US, one over-the-counter device is cleared for adults 18 and older who do not use insulin. [1] Whether it helps you is a separate question the evidence does not yet answer.

Will a glucose monitor help me live longer?

No source read for this page shows that. Trials measure blood sugar and behavior, not lifespan. [6][7]

Are smartwatches that read blood sugar reliable?

The FDA warns against devices that claim to measure glucose without piercing the skin. [2]

Is a glucose spike after eating dangerous?

The sources read here do not define a harmful spike for healthy people. Talk with your clinician about any concern. Healthy people also show wide variation in responses to the same meal. [5]

Do healthy people ever have low readings?

Yes, short periods of readings below 70 mg/dL were common in a study of people with normal glucose tests. [3]

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

What regulators say

In March 2024 the US FDA cleared the first over-the-counter CGM. It is intended for adults 18 and older who do not use insulin, including people who want to understand how diet and exercise may affect blood sugar. [1] The FDA says it is not for people with problematic low blood sugar, because it is not designed to warn of that, and that users should not make medical decisions from its output without talking to a health care provider. [1] Adverse events in the study included local infection, skin irritation and pain or discomfort. [1]

The FDA reported that in the clinical study the device performed similarly to other cleared sensors. [1] That is a statement about measuring glucose, not about whether wearing one improves health in people without diabetes. Label: approved device for measuring glucose; insufficient evidence for long-term health benefit.

A separate warning: the FDA says not to buy or use smartwatches or smart rings that claim to measure blood glucose without piercing the skin, and that these devices do not directly test blood glucose. [2] Those are a marketing claim, unlike skin-worn sensors that are FDA-authorized.

Who should check with a clinician first

The FDA states the over-the-counter device is for adults who do not use insulin and not for people with problematic low blood sugar, and that users should not make medical decisions from its output without talking to a health care provider. [1] Anyone taking diabetes medicines or with a history of low blood sugar should speak with their clinician first.

References

U.S. Food and Drug Administration. FDA Clears First Over-the-Counter Continuous Glucose Monitor (March 5, 2024). Read 2026-10-22.
U.S. Food and Drug Administration. Do Not Use Smartwatches or Smart Rings to Measure Blood Glucose Levels: FDA Safety Communication (February 21, 2024). Read 2026-10-22.
Reference metrics for continuous glucose monitoring in persons without diabetes and prediabetes. J Diabetes Sci Technol 2022. PMID 33100059. Read 2026-10-22.
Accuracy of continuous glucose monitoring in normo-glycemic individuals. PLoS One 2015. PMID 26445499. Read 2026-10-22.
Zeevi D, et al. Personalized nutrition by prediction of glycemic responses. Cell 2015. PMID 26590418. Read 2026-10-22.
Systematic review and meta-analysis of randomised trials of CGM as a behaviour change tool. Int J Behav Nutr Phys Act 2024. PMID 39716288. Read 2026-10-22.
Systematic review of non-invasive CGM in patients without diabetes for cardiovascular prevention. Sensors 2025. PMID 39796978. Read 2026-10-22.

Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.