[acb-diabetics] from "The Diabetic nNewsletter"

Fri Aug 13 23:36:37 GMT 2010

August 2010 - People with type 1 diabetes must keep a careful eye on their
blood glucose levels: Too much sugar can damage organs, while too little
deprives

the body of necessary fuel. Most patients must prick their fingers several
times a day to draw blood for testing.

To minimize that pain and inconvenience, researchers at MIT's Spectroscopy
Laboratory are working on a noninvasive way to measure blood glucose levels
using

light.

First envisioned by Michael Feld, the late MIT professor of physics and
former director of the Spectroscopy Laboratory, the technique uses Raman
spectroscopy,

a method that identifies chemical compounds based on the frequency of
vibrations of the bonds holding the molecule together. The technique can
reveal glucose

levels by simply scanning a patient's arm or finger with near-infrared
light, eliminating the need to draw blood.

Spectroscopy Lab graduate students Ishan Barman and Chae-Ryon Kong are
developing a small Raman spectroscopy machine, about the size of a laptop
computer,

that could be used in a doctor's office or a patient's home. Such a device
could one day help some of the nearly 1 million people in the United States,

and millions more around the world, who suffer from type 1 diabetes.

Researchers in the Spectroscopy Lab have been developing this technology for
about 15 years. One of the major obstacles they have faced is that
near-infrared

light penetrates only about half a millimeter below the skin, so it measures
the amount of glucose in the fluid that bathes skin cells (known as
interstitial

fluid), not the amount in the blood. To overcome this, the team came up with
an algorithm that relates the two concentrations, allowing them to predict

blood glucose levels from the glucose concentration in interstitial fluid.

However, this calibration becomes more difficult immediately after the
patient eats or drinks something sugary, because blood glucose soars
rapidly, while

it takes five to 10 minutes to see a corresponding surge in the interstitial
fluid glucose levels. Therefore, interstitial fluid measurements do not give

an accurate picture of what's happening in the bloodstream.

To address that lag time, Barman and Kong developed a new calibration
method, called Dynamic Concentration Correction (DCC), which incorporates
the rate

at which glucose diffuses from the blood into the interstitial fluid. In a
study of 10 healthy volunteers, the researchers used DCC-calibrated Raman
spectroscopy

to significantly boost the accuracy of blood glucose measurements - an
average improvement of 15 percent, and up to 30 percent in some subjects.

The researchers described the new calibration method and results in the July
15 issue of the journal Analytical Chemistry. In addition to Feld, Barman
and

Kong, authors include Ramachandra Rao Dasari, associate director of the
Spectroscopy Lab, and former postdoctoral associate Gajendra Pratap Singh.

Michael Morris, professor of chemistry at the University of Michigan, says
the group appears to have solved a problem that has long stymied
researchers.

"Getting optical glucose measurements of any sort is something people have
been trying to do since the 1980s," says Morris, who was not involved in
this

study. "Usually people report that they can get good measurements one day,
but not the next, or that it only works for a few people. They can't develop

a universal calibration system."

Morris says the noninvasive nature of Raman spectroscopy could help boost
quality of life for diabetes patients, but that to be practical, any device
would

need to become more affordable and very simple to use. The Spectroscopy Lab
researchers believe that the smaller machine they are now developing should

substantially drive down costs by miniaturizing and reducing the complexity
of the instrument.

Barman and Kong plan to launch a clinical study to test the DCC algorithm in
healthy volunteers this fall. Their work is funded by the National
Institutes

of Health and National Center for Research Resources.

In October, Barman will receive the Tomas A. Hirschfeld Award at the
Federation of Analytical Chemistry and Spectroscopy Societies Conference,
for his work

on improving spectroscopy-based glucose measurements.

Source: MIT 

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Researchers Develop Way to Measure Blood Glucose Levels by Shining Light on
the Skin

12-Aug-2010

August 2010 - People with type 1 diabetes must keep a careful eye on their
blood glucose levels: Too much sugar can damage organs, while too little
deprives