Digging deep to avoid scratching the surface: the quest for non-invasive glucose monitoring solutions continues

26 May – 1 June 2025 was Type 2 Diabetes Prevention Week in the UK, a joint campaign run by NHS England and Diabetes UK to raise awareness of the risk of Type 2 Diabetes and how to avoid it.

This campaign also serves to highlight the growing global prevalence of Type 2 diabetes and the growing global market for Continuous Glucose Monitoring (CGM) solutions - a market which the Med Tech industry is working hard to address.  Existing CGM solutions that require piercing of the skin have been available on prescription in many countries around the world for several years.  In March 2024, the U.S. Food and Drug Administration (FDA) also approved the first over-the-counter CGM solution for non-insulin users who are aged 18 or over.  However, to date, none of the FDA-approved CGM solutions are truly non-invasive with the result that the long and well-documented quest for accurate and reliable truly non-invasive glucose monitoring (NIGM) solutions continues¹. 

The general increase in health awareness in recent years has also led to an explosion in the number of wearable health monitoring devices on the market.  Some of these devices purport to measure blood glucose levels, even though they have not received FDA-approval for measuring blood glucose levels, prompting the FDA to issue a safety communication in February 2024 stating:

“The U.S. Food and Drug Administration (FDA) is warning consumers, patients, caregivers, and health care providers of risks related to using smartwatches or smart rings that claim to measure blood glucose levels (blood sugar) without piercing the skin. These devices are different than smartwatch applications that display data from FDA-authorized blood glucose measuring devices that pierce the skin, like continuous glucose monitoring devices (CGMs). 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.”

Patent filing statistics can provide a useful measure of R&D activity in a given technical area.  In this regard, FIG. 1 below shows the number of NIGM-related patent families published globally by earliest priority year since 2014:

FIG. 1 : Number of Published Patent Families Since 2014 by Earliest Priority Year for which the Terms ("Non-Invasive" AND "Glucose") OR ("Noninvasive" AND "Glucose") Appear in the Title or Abstract.

In FIG. 1, the number of published patent families for which the earliest priority year is 2020, 2021, or possibly even 2022, may have been impacted by the COVID pandemic.  Also, since many patent applications are not published until around 18 months from the earliest priority date, it is likely that a proportion of up to approximately 10% of the patent families for which the earliest priority year is 2023 have not been published at the time of writing and that the actual number of published patent families for which the earliest priority year is 2023 may be up to approximately 10% greater than that shown in FIG. 1.  Nevertheless, the patent filing statistics shown in FIG. 1 indicate that the number of NIGM-related patent families filed annually almost tripled from 2014 to 2023, suggesting a significant increase in NIGM-related R&D activity over the same time period. Many patent families for which the earliest priority year is 2024 or 2025 have not been published at the time of writing, but when patent family publication data becomes available for 2024 or 2025, it will be interesting to see whether the number of published NIGM-related patent families for which the earliest priority year is 2024 or 2025 exceeds the number of published NIGM-related patent families for which the earliest priority year is 2023 and, if so, by what margin.

Also notable is the diverse nature of the different technologies that are being investigated for use in NIGM, reflecting the “depth” to which researchers are prepared to “dig” to meet the technical challenges of NIGM and address the market for NIGM solutions.  For example, developments in NIGM have been described in research articles or press releases published in the last few years alone which rely on a variety of different optical techniques including a photoplethysmogram (PPG) technique in the visible and the NIR², time-gated photoacoustic spectroscopy using excitation in the mid-IR³, and Raman spectroscopy using NIR excitation⁴.  Recent publications also describe different microwave approaches^{5, 6}.

Given the ongoing investment in NIGM R&D, it will be fascinating to see which NIGM technologies achieve market success over the years to come so that people living with diabetes no longer have to “scratch the surface” of their skin in order to monitor their blood glucose levels.

[1] "The Pursuit of Noninvasive Glucose: Hunting the Deceitful Turkey", John L. Smith, 9th Edition, 2023

[2] “Non-invasive blood glucose estimation method based on the phase delay between oxy- and deoxyhemoglobin using visible and near-infrared spectroscopy”, Tomoya Nakazawa et al., Journal of Biomedical Optics, Vol. 29, Issue 3, 037001 (March 2024)

[3] “Non-invasive measurements of blood glucose levels by time-gating mid-infrared optoacoustic signals”, Nasire Uluç et al., Nature Metabolism volume 6, pages 678–686 (2024)

[4] “Calibration and performance of a Raman-based device for non-invasive glucose monitoring in type 2 diabetes”, Anders Pors et al., Scientific Reports volume 15, Article number: 10226 (2025)

[5] “Noninvasive blood glucose monitoring using a dual band microwave sensor with machine learning”, Mariam Farouk et al., Scientific Reports volume 15, Article number: 16271 (2025)

[6] “World-first wearable diabetes monitor being developed with EU funding boost”, Press Release, Welsh Government, 7 May 2025