Non-invasive blood glucose measurement

Researchers from Tohoku University have developed a harmless and non-invasive method of measuring blood glucose using far infrared light. Their technique could prove life-changing for the millions of diabetes patients around the world who monitor their daily glucose levels by taking a blood sample from their fingertips, undergoing pain and risk of infection on a regular basis.

Other researchers have proposed glucose measurement using near infrared light, working on the premise that the near infrared light of some wavelengths is selectively absorbed by glucose in the blood. However, accurate and stable measurement using this method has proven difficult because near infrared light is not only weakly absorbed by glucose, but also by water, protein and haemoglobin.

In contrast, far infrared light with wavelengths of around 10 microns is strongly absorbed by glucose, making it theoretically possible for patients to get more sensitive and accurate measurements. The problem is that far infrared light penetrates only a few microns from the skin’s surface, which makes the detection of blood glucose difficult.

The Japanese researchers, led by Professor Yuji Matsuura, developed a measurement technique that consists of a small prism attached to the ends of flexible hollow-optical fibres to radiate far infrared light. By using this method, it is possible to irradiate the oral mucosa of inner lips that, unlike skin, have no thick horny layer.

The team’s results show blood glucose levels sensitively detected and accurately measured with a less than 20% margin of error, which Professor Matsuura believes is good enough for clinical use. By combining the new method with recently developed far infrared lasers, Professor Matsuura expects compact and low-cost blood glucose measurement systems to soon be widely used in clinical fields.

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