Scientists Use Infrared Light to Measure Blood Glucose

Invasive blood sampling may no longer be necessary

Researchers in Japan have developed a new method for measuring blood glucose using harmless, noninvasive far infrared light (FIL). Diabetes patients traditionally monitor their daily blood glucose levels with a conventional meter, which requires blood sampling from the fingertips.

In the past, scientists developed noninvasive methods for glucose measurement using near infrared light (NIL). This method works on the premise that NIL of certain wavelengths is selectively absorbed by glucose in the blood. Accurate and consistent measurement using this technique was difficult, however, because NIL is weakly absorbed by glucose as well as by water, protein, and hemoglobin.

In contrast, FIL, with wavelengths of around 10 microns, is strongly absorbed by glucose, making it possible––theoretically––for patients to obtain more-sensitive and more-accurate measurements. However, the problem faced by researchers is that FIL penetrates only a few microns into the skin’s surface.

Researchers at Tohoku University’s Graduate School of Biomedical Engineering have developed a new technique to overcome this problem. The new method employs a small prism attached to the ends of flexible hollow-optical fibers to radiate FIL. With this technique, it is possible to irradiate the oral mucosa of the inner lips, which, unlike skin, do not have a thick horny layer, the researchers say.

In their experiments, blood glucose levels were measured in the oral mucosa with less than a 20% margin of error, which the investigators believe is good enough for clinical use.

Source: Tohoku University; February 4, 2016.