Checking glycemic index with NIR light

Reliable and noninvasive ways to check blood sugar have proved elusive, but a new effort by scientists at the National Food Research Institute could bring a near-infrared spectroscopy-based approach a step closer.

NIR seems tailor-made for glucose monitoring, but because conditions under which the test would have to be run vary so widely, a clinically acceptable method has not yet been devised.

The researchers report that they have achieved real progress, thanks to an approach that eliminates the person-to-person variation and involves sensing over a larger area of skin than had been attempted previously.

The glycemic index of foods can indicate the influence of that food on blood glucose levels, but glycemic index measurements are invasive as well as expensive in terms of both time and money. It works as follows: Taking a series of blood samples, scientists check the increase in blood glucose after a standard amount of a carbohydrate is consumed.

In the present study, the researchers demonstrated that the glycemic index can be determined without excessive blood sampling. They illuminated the palm of the hand, among other body parts, and then measured the light emitted, comparing it to previous measurements. Skin pigmentation did not affect the results, they reported.

The team now is using the technology to determine the glycemic index values of various foods. Their findings were published in the Journal of Near Infrared Spectroscopy, Vol. 18, Issue 5, pp. 291-300 (2010).