Non-Invasive and Experimental Glucose Monitoring

Introduction to Non-Invasive [Glucose Monitoring](/) (NIGM)

Non-invasive glucose monitoring (NIGM) means measuring glucose without breaking the skin: no fingerstick, no needle and no sensor filament. As of October 2026, it remains mostly a research field. In February 2024 the FDA said it has not authorized any smartwatch or smart ring that measures blood glucose on its own, and the authorized monitors it pointed to, such as continuous glucose monitors (CGMs), all pierce the skin [1]. Here's what surprised us in the FDA's records: a needle-free glucose monitor did win approval once, back in 2001 [4].

Technical Background

Researchers usually sort NIGM methods into three families by how they detect glucose: optical, microwave or radio-frequency (RF), and electrochemical [3]. Optical methods shine light into tissue and read how glucose changes its absorption or scattering, as in near-infrared or Raman spectroscopy. Electrochemical approaches either pull glucose out through the skin or read it from body fluids like sweat and tears [3]. In every case the device measures a physical signal that shifts with glucose, then relies on an algorithm to turn that signal into a glucose estimate [3]. Know Labs, for example, described its platform as using radio waves to identify and measure molecules [2].

Current State of NIGM Development

The old line that no non-invasive device has ever reached FDA approval doesn't hold up. The FDA approved the GlucoWatch Automatic Glucose Biographer in March 2001 [4]. Developed by Cygnus and worn like a watch, it used reverse iontophoresis, a small electric current that draws glucose out through intact skin to a sensor, and gave a reading every 20 minutes for up to 12 hours [5]. The approval covered adults (a 2002 supplement added children 7 to 17) and only as an adjunctive device, meaning it supplemented standard fingerstick meters rather than replacing them [4]. Each session needed a fingerstick reading to calibrate [6]. Users also dealt with skin irritation, a long warm-up and no readings while sweating [3][5]. Sales stopped in 2007 [3], and the FDA database lists the approval as withdrawn in April 2010 [4].

What about the big consumer-electronics brands? Apple and Samsung have been widely reported to be researching glucose sensing for watches. As of October 2026, though, no smartwatch from any brand is FDA-authorized to measure glucose by itself [1].

Two startups often named in this field have changed course. Know Labs renamed itself USBC, Inc. in August 2025 after an investor bought a controlling stake, and turned to financial technology [13]; on March 27, 2026, it sold its legacy non-invasive sensor business to a company controlled by its former chairman and CEO [10]. Rockley Photonics had been building an infrared optical sensing platform whose planned measurements included glucose trends [12]. It filed for Chapter 11 bankruptcy protection in early 2023 and emerged that June, saying its glucose monitoring program was continuing [11]. We found no update on that work from the company after 2023, so its current status is unclear.

The closest the market has come is minimally invasive rather than needle-free. On September 23, 2025, the FDA granted a De Novo request for Biolinq's Shine Autonomous Time-in-Range Microsensor as a prescription device [8]. (De Novo is the FDA's route for a new type of device that has no existing equivalent.) Instead of one filament, Shine uses seven tiny electrodes that sit in the upper layer of the dermis on the inner forearm. It measures glucose in interstitial fluid for up to five days and shows the result as a color-changing light rather than a number [9]. A 510(k) clearance on September 18, 2026, added over-the-counter use for adults 22 and older who don't take insulin [9]. It still breaks the skin, and as of October 2026 we couldn't confirm when it will be widely sold. For OTC sensors that use a conventional filament, see our over-the-counter CGM overview.

Three problems keep holding true non-invasive devices back:

• Signal specificity: glucose's signal overlaps with those of water and other substances in tissue, so algorithms have to separate it from strong background signals [3]
• Environmental interference: changes in skin temperature, body movement and sweat can shift readings [3]
• Accuracy: MARD (mean absolute relative difference) is the average percentage gap between a device's readings and reference blood glucose values, and lower is better. In one 92-person clinical analysis, the GlucoWatch's MARD was 15.6% [6]. The FDA's rules for integrated CGMs (iCGMs) don't set a MARD cutoff at all; among other tests, they require that across the full measuring range, more than 87% of readings fall within 20% of a matched blood glucose value, judged with a statistical confidence bound [7]

Regulatory Considerations

The FDA's safety communication, issued February 21, 2024, tells consumers, caregivers and clinicians not to buy or use smartwatches or smart rings that claim to measure blood glucose without piercing the skin [1]. It applies to every such device regardless of brand. The agency notes that dozens of companies sell them under many names and that they don't directly test blood glucose [1]. Its concern is practical: an inaccurate reading used for a medical decision can lead to serious injury or death [1]. The warning doesn't cover smartwatch apps that display data from an FDA-authorized CGM, and the FDA's advice for anyone whose care depends on accurate readings is to talk with their health care provider about an authorized device [1].

A non-invasive monitor meant to stand in for a CGM would need clinical evidence the FDA accepts. The iCGM special controls show what that evidence looks like for CGMs designed to send data to connected devices such as automated insulin dosing systems [7].

Future Directions

The open work is less about new physics than about proof:

• Better sensors and signal processing that can pick out glucose despite temperature changes, movement and background signals from skin [3]
• Clinical studies that compare device readings with blood glucose reference values, the kind of evidence behind both the GlucoWatch approval and Biolinq's De Novo authorization [5][8]
• Early work with the FDA on which pathway fits a new design; Biolinq's sensor, for instance, reached authorization through a De Novo request [8]

Conclusion

As of October 2026, the only needle-free glucose monitor we found in the FDA's approval records left the market years ago [3][4]. No smartwatch or ring is authorized to measure glucose [1], and recently authorized designs such as Biolinq Shine still sit just under the skin [9]. Which glucose monitor fits your treatment is a decision to make with your care team.