ATHENS, Ohio -- Scientists have edged one step closer to the development of a glucose measuring device that uses light instead of a blood sample. Such a diagnostic tool would offer millions of diabetics a painless option for keeping their disease in check.
People with diabetes must diligently monitor the amount of glucose in their blood, which requires patients to apply needles to fingertips as often 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 Iowa suggests that a technique that passes infrared light through the skin can accurately measure blood glucose, research that one day could eliminate the need for a blood sample test.
"Most people feel that if you have a test that is noninvasive, diabetics would use it more often and probably do a better job of managing their disease," says Gary Small, a professor of chemistry at Ohio University who co-authored the new study with Mark Arnold, professor of chemistry at the University of Iowa. The research appears in the latest issue of the journal Diabetes Technology and Therapeutics.
In a small clinical trial involving five people with Type I, or insulin-dependent, diabetes, researchers used light to measure blood glucose up to six times a day for 39 days. Researchers shot a beam of infrared light through the tongue, which has a good blood supply.
Glucose and other molecules in the blood absorb specific frequencies of light. As the researchers couldn't see this happening in the tissue, they analyzed the light emerging from the tongue. By measuring the degree to which each light frequency was absorbed by the tongue, the researchers were able to determine how much glucose was in the blood.
Although the apparatus designed for these studies is expensive and impractical for home use, researchers envision a light-based glucose monitor that would be about the size of a portable CD player and probably cost 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 clinical trials to be simplified and made potentially cheaper, smaller and more rugged. 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 a terrible place for a home monitor," Arnold says. "Eventually, we'd want to be able to make the measurements on a fingertip or ear lobe."
This isn't the first study to suggest infrared light can be used to measure blood glucose. Other researchers have presented data that suggested the theory had merit. But a 1998 article by Small and Arnold in the journal Analytical Chemistry argued that those earlier studies were done on tissue too thin to contain enough glucose for an accurate reading. The paper also questioned the credibility of previous experimental protocols. Any correlation between the amount of infrared light detected through tissue and glucose levels, they argued, was coincidental.
"Our new findings represent what we feel is the first comprehensive demonstration that noninvasive measurements can be made with infrared light," Small says.
Now that they know the technique works, the research team plans to improve the performance of the method. Small estimates the technique could be ready for commercial use in three to five years.
The research was also co-authored by Jason Burmeister at the University of Iowa and was supported by the National Institutes of Health and Inverness Medical Technology. Small holds an appointment in the College of Arts and Sciences.
Written by Kelli Whitlock.
Contacts: Gary Small, Ohio University, 740-593-1748; small@ohio.edu
Mark Arnold, University of Iowa 319-335-1368; mark-arnold@uiowa.edu
Journal
Diabetes Technology & Therapeutics