Observation of blood glucose concentration variability with near-infrared spectroscopy technique

Diabetes is a metabolic disorder that occurs due to the fact that apparent glucose concentration is not balanced by the body. Diabetics should regularly monitor their blood glucose concentration value to avoid complications of diabetes. Until 1970s, this monitoring process could not be done in houses but with developing technology, it became possible. The glucose concentration monitoring systems in use get measurement by invasive, minimally invasive and non-invasive techniques respectively. In the first generation and the second generation measurement systems, invasive techniques have been used. However, since invasive measurement causes discomfort, and it kills some nerves cells and also it posses the risk of infection, conducted studies focus mainly on non-invasive techniques. Until now, numerous techniques have been used and innumerable studies have been carried out for non invasive measurements. Some of these studies have achieved to get partially sensitive measurements clinically. However, among the used techniques in conducted non-invasive measurement studies, Near Infrared Spectroscopy is the most successful one which also posses high potential to provide more sensitive results. In this work, we mainly focused on near infrared spectroscopy and we conducted experimental works by using this technique. The near infrared spectroscopy is a techniques that based on the absorbance ratios in the environment where the light passes. Measurement interval is between 750 nm and 2500nm. In this interval, many components inside the blood cells interact with light. This interaction provides information about the distribution of components in blood. In this work, glucose which is one of the main components of blood cells was examined in detail. Glucose absorption ranges and also glucose's reactions to the near infrared light were monitored. Experimental work was conducted on three volunteers. In these experiments three different light sources with three different wavelength were used. In experimental work, experimental scenario was developed to observe the glucose changes. According to this scenario, there were totally 3 different measurement time which can be listed as hungry state, glucose loading state 1 and glucose loading state 2. Totally, 27 different measurements were gotten from each volunteers where each measurement takes nearly 30 seconds. According to the results of conducted experiments, there is a strict relation between the amount of glucose level in the blood cells and the absorbance of the light. It is observed that this relation has nonlinear behavior. In measurements, the environmental effects and any movement occured in measurement platform would cause a notable effect which should not be ignored. Moreover, with having more stable probe design, measurements would be more reliable. As a future work, humidity and temperature sensors can be added to the current probe design so as to reduce the environmental effects. In order to make probes more stable, necessary design that enables all electronic components stay stable would be done.