Study Suggests Diabetics Can Use Light To Measure Glucose

Mark Arnold, University of Iowa (319) 335-1368; mark-arnold@uiowa.edu

ATHENS, Ohio – Scientists have edged one step closer to the development of a glucose measuring device that uses light instead of a blood sample. Sucha diagnostic tool would offer millions of diabetics a painless option forkeeping their disease in check.

People with diabetes must diligently monitor the amount of glucose intheir blood, which requires patients to apply needles to fingertips asoften as a half-dozen times a day. The routine is painful and inconvenient,two factors doctors say often deter healthy maintenance of the disease.

But a new study by chemists at Ohio University and the University of Iowasuggests that a technique that passes infrared light through the skin canaccurately measure blood glucose, research that one day could eliminate theneed for a blood sample test.

"Most people feel that if you have a test that is noninvasive, diabeticswould use it more often and probably do a better job of managing theirdisease," says Gary Small, a professor of chemistry at Ohio University whoco-authored the new study with Mark Arnold, professor of chemistry at theUniversity of Iowa. The research appears in the latest issue of the journalDiabetes Technology and Therapeutics.

In a small clinical trial involving five people with Type I, orinsulin-dependent, diabetes, researchers used light to measure bloodglucose up to six times a day for 39 days. Researchers shot a beam ofinfrared light through the tongue, which has a good blood supply.

Glucose and other molecules in the blood absorb specific frequencies oflight. As the researchers couldn't see this happening in the tissue, theyanalyzed the light emerging from the tongue. By measuring the degree towhich each light frequency was absorbed by the tongue, the researchers wereable to determine how much glucose was in the blood.

Although the apparatus designed for these studies is expensive andimpractical for home use, researchers envision a light-based glucosemonitor that would be about the size of a portable CD player and probablycost around $500. Ohio University and the University of Iowa share two U.S.patents on the data analysis techniques used in the researchers' studies,including a method that would allow the instrument used in the clinicaltrials to be simplified and made potentially cheaper, smaller and morerugged. But the target of such a commercial device wouldn't be the tongue.

"The tongue makes a great place for measuring glucose in our tests, but aterrible place for a home monitor," Arnold says. "Eventually, we'd want tobe able to make the measurements on a fingertip or ear lobe."

This isn't the first study to suggest infrared light can be used tomeasure blood glucose. Other researchers have presented data that suggestedthe theory had merit. But a 1998 article by Small and Arnold in the journalAnalytical Chemistry argued that those earlier studies were done on tissuetoo thin to contain enough glucose for an accurate reading. The paper alsoquestioned the credibility of previous experimental protocols. Anycorrelation between the amount of infrared light detected through tissueand glucose levels, they argued, was coincidental.

"Our new findings represent what we feel is the first comprehensivedemonstration that noninvasive measurements can be made with infraredlight," Small says.

Now that they know the technique works, the research team plans to improvethe performance of the method. Small estimates the technique could be readyfor commercial use in three to five years.

The research was also co-authored by Jason Burmeister at the University ofIowa and was supported by the National Institutes of Health and InvernessMedical Technology. Small holds an appointment in the College of Arts andSciences.

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Written by Kelli Whitlo