HQ Team
March 29, 2024: The last few years have seen many innovative devices that help in monitoring blood sugar without finger pricks.
The latest addition to these technologies utilizes signal localization to improve the accuracy of non-invasive glucose measurement (NIGM).
Non-invasive devices
There are several devices approved by the FDA in the market that measure blood glucose levels including from Abbott, Dexcom, and other pharmaceutical companies that use sensors to measure glucose from interstitial fluids just underneath the skin.
There are some limitations to these devices as the intestinal measurement is not as accurate as a blood sample. Also, the micro needles in the device can cause skin infections.
Hence, the search for needle-less technology to measure glucose levels such as terahertz (THz) spectroscopy. It is based on light absorption. However, this measurement utilises a broad spectrum band and can mistake glucose for other biomolecules.
Another new form of CGM (continuous glucose monitoring) created by DiaMon Tech uses heat to measure blood sugar levels. The innovative technology uses an infrared laser targeted at the skin that causes the glucose in the skin to convert the light to heat. The increase in the heat levels is used to measure the glucose levels. In preclinical tests, it was found to be as accurate as test strips.
Optoacoustic method
The present study focuses on the use of mid-infrared (mid-IR) light absorption, which uses optical, optoacoustic, or thermal detection methods to measure blood glucose levels. The depth-gated mid-infrared optoacoustic sensor (DIROS) exploits time-gated mid-IR optoacoustic signals to determine the exact depth at which glucose absorption is measured in the skin, as a result, it can measure real-time blood glucose levels rather than ISF glucose.
Importantly, DIROS can minimise potential errors in measurement due to variations in skin humidity or the presence of fats and other molecules on the skin.
Study
The researchers measured the Mid-IR of blood glucose levels on a mouse ear using depth-selective optoacoustic detection. These were verified against measurements obtained by optoacoustic measurements from the capillaries at 532 nm illumination.
Optoacoustic sensing was used to reach the dermis and epidermis at 100 micrometers (µm) and more. This depth is rich in capillaries, thus making real-time blood glucose assessment possible.
Using nearly 5,000 optoacoustic measurement points, accurate blood glucose values with sufficient signal-to-noise ratios (SNR) were also obtained.
The researchers obtained measurements from two locations, one rich in blood capillaries (P1) and the other slightly less dense in capillaries(P2). P1 values were closer to the glucometer-recorded blood glucose concentrations as compared to the P2 values; however, both values changed after glucose was administered. P2 values changed more slowly, thus reflecting the delayed changes in ISF glucose.
Future
The investigators explored the utility of depth selection to enhance DIROS performance beyond that of currently available sensors.
DIROS could help increase the precision of blood glucose measurement non-invasively and advance diabetes management.
The study can be accessed in the journal Nature Metabolism.
