Glucose – Not A Single Minute Without Surveillance

An amazing device has been invented by the St. Petersburg physicists – specialists of the Vavilov State Optical Institute. With its help, a patient can learn the glucose concentration in the blood without injections, and if the concentration is rather high, to inject additional amount of insulin into the blood.

The device is an artificial pancreas and it will consist of two parts. One part, according to the developers’ idea, is slightly larger than a watch battery and can be implanted under the skin near the waist. The other part, the size of a cigarette pack, will be attached outside the body.

Unfortunately, hundreds of thousands people know about insulin-dependent diabetes from their own experience. Because of the pancreas’ malfunction have to test their blood several times a day to learn the glucose concentration and to find out if another insulin injection is needed. This would be relatively simple if the organism worked strictly according to the schedule and a person could say precisely when it is necessary to inject insulin and in what amount. However, in reality, everything is more complicated: the glucose level changes under its own laws, and a simple schedule of injections does not always help.

If a person is healthy, the problem is simply solved by his/her own pancreas. If required, it would add to the insulin “discharge”, if this is not required – it would reduce it. If a person is sick, his/her pancreas fails to handle the task. So the researchers are trying to produce an artificial pancreas, they have been trying for about twenty-five years with varying success. Research by St. Petersburg physicists promises a significant breakthrough.

“The essence of our method is that it allows to identify glucose and to determine its concentration against a background of multiple other components of blood – by the glucose two-dimensional spectral image, says Vladimir Chuvashov, Ph. D. (Engineering), manager of research. That is, the method allows to measure the glucose content in parallel in one beam by two ways – both by the spectroscopic and the polarimetric ones.

“Practically all earlier developments are based on one-dimensional spectral images. The difference in quality of glucose recognition is approximately the same as between one-dimensional and two-dimensional dactyloscopic skin print in the course of person identification. The method we are developing can be used for glucose identification both in the ophthalmic fluid (this is a non-invasive option) and in the corporeal one (implantable option)”.

In the second case, measurement takes place in the part of the device that is under the skin. It is connected with the help of the optical communications fiber line with the external part where a semiconductor laser is located along with micro-devices for analysis of the signal obtained in the course of the analysis.

So, a small laser generates irradiation. The laser beam is directed under the skin along the optical fiber, i.e. part of glass fiber. The beam is partly absorbed, partly dispersed, and partly reflected. The important thing is that glucose (due to structure of its molecules) changes the beam parameters to some extent. Firstly, it changes the plane of optical polarization, and it is known to what extent. Secondly, it changes intensity of scattered radiation proportionally to the properties inherent in glucose (physicists specify – “due to fundamental absorption bands caused by vibration frequency of a glucose molecule”).

The light which has changed as a result of interaction with the tissue and substances dissolved in intercellular fluid, returns back to the device again along the waveguide. The beam should be analyzed there, so that in the long run a person could determine the glucose concentration in this fluid. To this end, respective devices – spectrometers – are required. Large spectrometers are no problem for a long time, they have been well-known for long. It is difficult to design small ones – so that it would be convenient to carry them all the time.

There are multiple private companies worldwide that deal with similar developments on a competitive basis, and many technical solutions are already known. Detailed development is certainly necessary anyway, but this problem is solvable, and researchers already know the way to solve it. Especially because they deal with the problem jointly with colleagues from the internationally known Ioffe Physical & Technical Institute. On the other hand, several years ago, they already managed to produce a pre-production model of a similar device – a pocket polarimeter for identification of glucose in urine. Therefore, the researchers possess the necessary experience and knowledge.