Non-invasive blood sugar monitoring

A team of German researchers has devised a novel, non-invasive way to make monitoring of blood glucose easier.

There are already lots of blood glucose monitoring devices on the market but they all require a drop of blood. Many diabetics have to prick their fingers multiple times a day to measure their glucose levels. Apart from being painful, there is always the risk of peripheral nerve damage and infection.

Now, a German team, led by Werner Mäntele from Frankfurt's Institut für Biophysik, Johann Wolfgang Goethe-Universität, has developed a system that uses infrared laser light applied on top of the skin to measure sugar levels in the fluid in and under skin cells to read blood sugar levels. The method is described in the current edition of Review of Scientific Instruments.

This optical approach uses photoacoustic spectroscopy (PAS) to measure glucose by its mid-infrared absorption of light. A painless pulse of laser light applied externally to the skin is absorbed by glucose molecules and creates a measurable sound signature that Mäntele’s team refers to as "the sweet melody of glucose". This signal enables researchers to detect glucose in skin fluids in seconds.

The data showing the skin cell glucose levels at one-hundredth of a millimetre beneath the skin is related to blood glucose levels, Mäntele said, but previous attempts to use PAS in this manner have been hampered by distortion related to changes of air pressure, temperature and humidity caused by the contact with living skin.

To overcome these constraints, the team devised a design innovation of an open, windowless cell architecture. While it is still experimental and would have to be tested and approved by regulatory agencies before becoming commercially available, the team continues to refine it.

In a close collaboration with industry partner Elte Sensoric, they expect to have a small shoebox-sized device ready in three years, followed by a portable glucometer some years later.

The article, Windowless ultrasound photoacoustic cell for in vivo mid-IR spectroscopy of human epidermis: Low interference by changes of air pressure, temperature, and humidity caused by skin contact opens the possibility for a non-invasive monitoring of glucose in the interstitial fluid, is authored by Miguel A Pleitez, Tobias Lieblein, Alexander Bauer, Otto Hertzberg, Hermann von Lilienfeld-Toal and Werner Mäntele.

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