Non-Invasive Glucose Monitoring Technology

Non-Invasive [Glucose Monitoring](/) Technology

As of October 2026, there is no FDA-authorized glucose monitor you can buy that works without entering the skin. In February 2024 the FDA said it has not authorized, cleared or approved any smartwatch or smart ring that measures or estimates blood glucose on its own, and it told consumers not to buy or use them [1]. The authorized devices that come closest make the sensor smaller or shallower. None of them removes it.

What "non-invasive" means, and what it doesn't

A non-invasive monitor would read glucose without breaking the skin at all: no lancet, no needle, no sensor wire. A 2022 review in the Journal of Diabetes Science and Technology sorted bloodless glucose products into three groups. Non-invasive optical devices send light or other energy through intact skin. Non-invasive fluid-sampling devices collect sweat, tears or fluid pulled out through the skin. Minimally invasive devices still enter the skin, just less deeply than a fingerstick [2]. The authors counted 28, 6 and 31 products in those groups [2].

By that scheme, the continuous glucose monitors (CGMs) people wear are minimally invasive. They also don't read blood glucose directly. They read glucose in interstitial fluid, the fluid that surrounds the cells just under the skin. The FDA files for Dexcom's Stelo and Abbott's Lingo both describe a small sensor inserted into the tissue under the skin that measures interstitial fluid glucose [3][4].

What the FDA warned about in 2024

The safety communication, dated February 21, 2024, applies to any smartwatch or smart ring that claims to measure glucose without piercing the skin, whatever the brand [1]. According to the FDA, dozens of companies make these devices under many brand names and sell them through online marketplaces or directly. The agency adds that they don't directly test blood glucose at all [1].

Its worry is concrete. A wrong reading can lead someone to take the wrong dose of insulin, a sulfonylurea or another drug that lowers glucose quickly, and too much of these drugs can bring on dangerously low glucose within hours [1].

The warning has a clear edge. It doesn't cover smartwatch apps that display readings from an FDA-authorized CGM that pierces the skin [1]. If your watch shows numbers sent from a sensor on your arm, that's a different product, and our article on direct-to-watch CGM architectures explains how that data gets there. As of October 2026, the FDA page still carries its original February 2024 date [1].

What the FDA has authorized

Here's what surprised us. The FDA keeps a product code for exactly this idea, NCT, "Instrument, Glucose, Noninvasive Technology," and as of October 2026 its classification record links to a single premarket approval, P990026 [5]. That approval belonged to the GlucoWatch Automatic Glucose Biographer, approved on March 22, 2001 and withdrawn on April 23, 2010 [6]. It worked by drawing fluid through the skin with a small electric current, which is why the 2022 review files that approach under fluid sampling rather than optical sensing [2]. Our article on non-invasive glucose sensing technologies tells the GlucoWatch story and walks through the physics of each sensing method.

What you can get today shrinks the sensor instead of removing it.

• Over-the-counter CGMs. The FDA cleared Stelo in March 2024 and Lingo in May 2024 as over-the-counter integrated CGMs for people not on insulin [3][4]. Both use a small sensor inserted under the skin [3][4].
• An intradermal microsensor. The FDA granted the Biolinq Shine De Novo authorization in September 2025 as a prescription device [7]. Its seven microelectrodes sit in the papillary dermis, the layer just below the skin's surface, and the device stores up to five days of data [8]. A clearance dated September 18, 2026 added over-the-counter use without changing the sensor [8]. The label covers adults 22 and older not on insulin, shows a color light rather than a number, and says users aren't meant to act medically on its output without talking to a qualified health care professional [8].
• A long-term implant. The Eversense 365 sensor is inserted under the skin by a health care provider and measures glucose for up to a year in adults 18 and older [9]. It reads glucose optically, from a fluorescent coating whose glow grows brighter as more glucose binds to it [9]. So optical glucose sensing already has an FDA-authorized home. It just sits under the skin instead of looking through it.

What hasn't been authorized

None of the 28 non-invasive optical products in the 2022 review was cleared by the FDA [2]. At least two had a European CE mark: GlucoTrack from Integrity Applications, marked in 2013 and 2014, and Cnoga Medical's TensorTip Combo Glucometer. The review lists both as not FDA-cleared [2]. The same table marks many uncleared products as "patented technology" [2], a reminder that a patent shows what a company claimed, not that a device works or may be sold. The authors also name products that were announced and then disappeared from public view, including a glucose-sensing contact lens that Novartis developed with Verily [2].

Biolinq shows how fast a listing can change. The 2022 review had the company's sensor down as not cleared [2]; by September 2025 the FDA had authorized the Biolinq Shine [7]. It got there by staying minimally invasive.

Why accuracy is the sticking point

The review lists what an optical monitor has to correct for: skin pigmentation, surface roughness, skin thickness, breathing, blood flow, body movement and ambient temperature [2]. It calls accuracy over time the major analytical challenge for every non-invasive optical technology [2]. Skin color is a specific concern. The authors point to the FDA's warning that pigmentation can affect pulse oximeters, and say each optical glucose system has to be tested for that effect at its own wavelengths [2]. Cost is the other barrier they name: prices have to fall before any of these devices can reach large populations [2].

How to check a "non-invasive" claim

• A watch or ring that reads glucose by itself. The FDA's answer, as of October 2026, is that none is authorized [1].
• Look for an FDA record. Each authorized device in this article has a numbered FDA file, such as K234070 for Stelo, DEN240080 and K262599 for Biolinq Shine, and K241335 for Eversense 365 [3][7][8][9]. Higher-risk devices generally need premarket approval, while many moderate-risk devices reach the market through 510(k) clearance [10].
• "FDA registered" is not approval. The FDA says registering a company or listing a device does not mean the device is approved or that it may be legally marketed [10].
• A CE mark or a patent isn't FDA authorization. GlucoTrack had a CE mark and no FDA clearance [2].
• Read who the device is for. Labels set limits, such as adults not on insulin, and some say the device isn't meant for medical decisions on its own [8].

The FDA asks people to report inaccurate readings or other problems with an unauthorized watch or ring through its MedWatch program [1]. Which glucose monitor fits your diabetes care is a decision for you and your care team.

What nobody can say yet is whether any light-based or radio-frequency sensor can read glucose through intact skin accurately enough, across every skin tone, to earn an FDA authorization. As of October 2026, the only record under the agency's non-invasive glucose product code is an approval that was withdrawn in 2010 [5][6].