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No smartwatch or smart ring has been authorized in the United States to measure blood glucose on its own, and no noninvasive glucose device is FDA-approved for clinical measurements. Measuring glucose through intact skin is a serious scientific goal, and laboratory prototypes exist, but the devices that people can rely on for diabetes decisions still require a finger-stick or a sensor placed under the skin.
What “seeing glucose through the skin” means
The phrase covers any method that estimates glucose without drawing blood and without inserting a sensor. Most experimental approaches do not detect glucose directly. They send a physical signal into tissue, usually light, and try to isolate a pattern in the returning signal that tracks glucose concentration. The same signal also carries information about the skin and surrounding tissue and about the conditions of the measurement, so the glucose component has to be separated from everything else. That separation is the central engineering problem.
How optical approaches try to read glucose
The American Diabetes Association’s 2023 laboratory guideline reviews several optical methods, including near-infrared, mid-infrared and Raman spectroscopy, among others. Each one works differently and faces different obstacles.
Mid-infrared spectroscopy
Mid-infrared light can be tuned to molecular vibration bands associated with glucose. This is the approach used in the most recent clinical study covered below. Because the bands are specific, mid-infrared work focuses on picking out a glucose signature from the background of skin tissue.
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Near-infrared spectroscopy
Near-infrared methods have been studied for years as a noninvasive option. They penetrate tissue more deeply than mid-infrared light, but the absorption features that relate to glucose overlap with those of water and other tissue components, which makes the glucose signal harder to isolate.
Raman spectroscopy
Raman techniques measure light that is scattered from molecules in tissue after interacting with them. Like the other optical methods, Raman work remains experimental for glucose, and the same separation problem applies.
Why skin is hard to read reliably
Skin contains interstitial fluid, which is relevant to glucose sensing, but the optical signal reflects that fluid only indirectly. Several factors are associated with unstable or inaccurate readings in the most detailed study of a noninvasive prototype:
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- Device instability. Small changes in the instrument itself alter the signal.
- Skin inhomogeneity. Skin is not uniform from one spot or one person to another, so a calibration built on one area may not transfer to another.
- Movement artifacts. Motion during measurement distorts the signal.
- Skin-care products. Lotions and other products on the skin can change what the instrument detects.
What the 2025 D-Base clinical study showed
Kaluza and colleagues published “Clinical validation of noninvasive blood glucose measurements by midinfrared spectroscopy” in Communications Medicine, online on November 15, 2025. The prototype, developed by DiaMonTech and called D-Base, uses a quantum-cascade laser to excite glucose in skin and photothermal deflection to detect the resulting signal.
- Design: a prospective, single-center study of 36 participants.
- Calibration: measurements were taken across sessions that used different amounts of calibration data.
- Accuracy: the best-performing algorithm reached a mean absolute relative difference (MARD) of 20.7% in one evaluation session and 19.6% in the other.
MARD is the average size of the gap between the device’s reading and a reference blood glucose value, expressed as a percentage of that reference. As an illustration only, a 20% MARD at a reference of 100 mg/dL would correspond to an average miss of about 20 mg/dL. These are the results of the best algorithm in a laboratory setting, not the typical performance a user would experience, and they do not show that noninvasive technologies in general perform similarly.
The study also places the device in context. Its handheld form, D-Pocket, is described as under development, and a wearable form is presented as a future concept. The paper reports no broadly available market comparison of noninvasive glucose monitors; the comparison it can draw is limited to data from the research group and the manufacturer.
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What the FDA says about smartwatches and smart rings
On February 21, 2024, the U.S. Food and Drug Administration issued a safety communication stating: “The FDA has not authorized, cleared, or approved any smartwatch or smart ring that is intended to measure or estimate blood glucose values on its own.”
The agency warns that inaccurate glucose readings can lead to errors in diabetes management, including taking too much insulin or other glucose-lowering medication, which can cause dangerously low blood glucose. It advises people whose care depends on accurate readings to talk with a health care provider about an FDA-authorized device. The FDA’s position applies to the United States; the cited sources do not establish the regulatory status of such products in other countries.
Established options and how they compare
Today’s glucose tools all involve skin penetration, though they differ in how often they measure and what they require. The table compares the main categories, including the intact-skin claims covered above.
Quick Recap
| Option | How glucose is obtained | Measurement pattern | Calibration and practical requirements | Authorization status |
|---|---|---|---|---|
| Finger-stick blood glucose meter | Drop of blood from a fingertip, tested on a strip | Spot checks when you test | Requires compatible test strips; calibration requirements not stated in the cited sources | Regulatory status not addressed by the cited sources |
| Continuous glucose monitor, Eversense E3 | Sensor implanted under the skin by a doctor (minimally invasive, not through-skin) | Values sent to a smart device every five minutes | Fingertip blood calibration required when prompted; sensor worn up to 180 days | FDA-approved March 29, 2023 (P160048/S021); prescription system for adults with diabetes |
| Smartwatch or smart ring claiming glucose on its own | Claimed to be noninvasive, with no blood drop or sensor | Not established | No authorized glucose value to calibrate against | Not authorized, cleared, or approved by the FDA (February 21, 2024) |
| D-Base research prototype | Laser-based measurement through intact skin, in a clinical study | Session-based study measurements | Calibration data amounts varied across study sessions | Research prototype; not authorized for consumer or treatment use |
If you need glucose numbers for treatment decisions
- Check whether the device’s glucose function has FDA authorization or clearance for its stated use. If a seller cannot name one, treat the glucose claim as unauthorized.
- Use a finger-stick meter or a continuous glucose monitor that your clinician has chosen for dosing decisions. A meter kit with compatible test strips is a finger-stick device; it does not measure through intact skin.
- Do not adjust insulin or other glucose-lowering medication based on a smartwatch or ring reading. Confirm the number with an authorized method first.
- Ask your health care provider which FDA-authorized device fits your treatment plan, especially if you have frequent lows or rely on alerts.
What remains uncertain
- The most detailed clinical evidence cited here comes from one center with 36 participants, so it cannot show how the device performs across different populations or conditions.
- The FDA statements are specific to the United States, and the sources do not establish the status of every device worldwide.
- No controlled comparison of consumer noninvasive devices was identified in the cited sources.
- This article reflects sources dated through November 2025. Newer trials or clearances may exist and are not covered here.
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