Glycaemic index measured using NIR spectroscopy

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Research published recently Journal of Near Infrared Spectroscopy (JNIRS) by a team of scientists at the National Food Research Institute, Tsukuba, Japan could one day offer diabetics a reliable and non-invasive technique for checking their blood glucose levels by conducting a simple measurement on the palm of the hand.

A reliable, non-invasive technique for checking blood glucose has eluded medical analysts despite many years of research by teams in many countries. While near infrared (NIR) spectroscopy is well suited to the task, the wide variety of conditions under which the test would have to be run has hitherto precluded a clinically successful solution. However, by eliminating the variation due to person-to-person differences and by examining a large area of the skin, the Japanese team believes that real progress has been made.

The glycaemic index (GI) of foods is a valuable indicator for diabetics of the influence that consuming the food will have on blood glucose levels. GI assessments are time consuming, expensive and invasive to the patient, as a series of blood samples are needed to check the increase in blood glucose after consuming a standard amount of a carbohydrate. Professor Sumio Kawano and colleagues, who lead the research, have now demonstrated that GI can be determined without the need for an excessive number of blood samples, simply by recording the light emitted when the palm of the hand is illuminated. Furthermore, the results are not affected by skin pigmentation.

'Earlier studies with near infrared methods were non-invasive, but unreliable from patient to patient,' said Professor Kawano. 'We have improved the reliability of blood glucose determinations with GI as our primary focus. We simply shine a light on the palm of the hand and measure the near infrared light which comes back.' The team, which includes PhD student Yasuhiro Uwadaira, used various parts of the body and small and large sensors in their work. They are now applying the technology to assess the GI values of a range of foods.