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Painless Blood-Sugar Tests in the Works

New Devices Work by Infrared Light

From the WebMD Archives

June 19, 2002 -- Do you have diabetes? Are you tired of pricking your fingers day in and day out? Well, you may soon have a painless way to make sure your blood sugar is in check -- thanks to infrared light.

Companies around the world are working to perfect such infrared devices, and four of them presented studies showing good progress at the annual meeting of the American Diabetes Association.

For more than 20 years, diabetics have been pricking their fingers and putting a drop of blood in a home monitoring instrument. On average, they do the test twice a day, but studies show they would be healthier if they did it much more often. But that just means more pain, right?

Not if new research pans out -- and things look pretty good so far.

Since few people want to prick their fingers constantly, researchers have been developing other techniques. In March 2001, the FDA approved the GlucoWatch Biographer. Worn on the wrist like a watch, the device uses electricity to painlessly draw tiny amounts of fluid from the skin and measure the sugar in it.

The amounts of sugar in the skin rise and fall in patterns similar to those in blood sugar. But since the measurements are not the same, diabetics must still prick their finger to verify the results of the GlucoWatch. Also, the device causes skin irritation in some people.

At the diabetes conference, teams of international researchers presented studies on devices that measure sugar in the skin by using infrared beams. In the largest study, researchers tested 139 type 1 diabetics over eight weeks. They found that the machine could accurately estimate their blood sugar levels through infrared readings taken on the forearm.

Currently the device is about the size of a VCR, but Instrumentation Metrics of Chandler, Ariz., expects to miniaturize it to the size of a cell phone. The company has an advantage over its competitors because it is farther along in the research, said CEO Don Hetzel, PhD, an organic chemist. "The other people haven't done large human trials."

In contrast to these devices, a different infrared monitor being developed by OrSense of Rehovot, Israel, measures sugar in the blood rather than the skin so its readings can be directly compared to the traditional finger prick tests. A preliminary study in six people suggested that its readings correlate much more closely with the traditional blood tests than do its rivals. "To the best of our knowledge, our method is unique because we measure blood," said the device's inventor, Ilya Fine, PhD, a biophysicist and OrSense's chief technology officer. "Blood is the gold standard."

Other attempts to measure blood sugar with infrared light have fallen short because, when shining a light through a body part, it is difficult to determine what tissue or fluid is affecting the light -- and thus the measurement. The OrSense device gets around that problem by squeezing the finger to make the circulation stop and then start again, Fine said. Blood flowing in this way affects infrared light in a distinctive way that can be analyzed to reveal the amount of blood sugar.

Like the Instrumentation Metrics device, the OrSense monitor is being refashioned to the size of a cell phone. Patients will put their finger in a hole in the instrument, feel a slight squeeze like that of a blood pressure cuff, then get their blood sugar reading. OrSense plans to start tests with a larger number of people at the end of this year.

"I think this has some potential," said David C. Klonoff, MD, a University of California, San Francisco, professor of medicine who reviewed the new blood sugar devices at the diabetes conference. Though the Instrumentation Metrics device may be equally promising, in regard to the OrSense monitor, he said, "I haven't seen anything that looks better."