Scientists are hard at work looking for ways people with diabetes can measure their blood sugar without the painful and scarring jabs now neccesary for blood collection.
Several researchers discussed the state of the art at a symposium in August 2002 at the American Chemical Society's annual meeting.
Dr. Yizhong Yu, chief scientist at Animas Corporation in Frazer, Pennsylvania, discussed his company's efforts to develop a tiny, titanium-coated device that would communicate continuous blood glucose readings to a monitor worn on the patient's wrist. Sensors would poke through a blood vessel wall to gauge the blood's absorption of near-infrared light.
The device, roughly the size of a pacemaker, would convert these readings to blood glucose levels, and is intended to last for at least 5 years in the body.
One major hurdle in developing devices that use light to measure blood glucose has been coming up with a formula to convert light wavelength readings into glucose levels. Yu reported that blood tests from more than 500 patients--far more than other companies developing similar devices--have shown Animas's formula is quite accurate.
Human tests will likely begin in a year or less, Yu said. But, he added, "I do not want to paint a very rosy picture...there is a lot for us to do to really get a sensor to the market." He told Reuters Health he could not estimate the price of the device, but said it would be a cost insurers would be comfortable paying.
Animas's device, Yu and other panelists at the meeting said, is the furthest along among other similar implantable devices under development.
Researchers are also investigating a completely non-invasive method: measuring wavelengths of near-infrared light after it passes through the skin. Dr. Mark A. Arnold of the University of Iowa in Iowa City reported on his efforts using this method.
After about 9 years, Arnold said, he and his colleagues are ready to begin clinical tests of a system in which a beam of light is passed through a roughly 2 millimeter pinch of skin at the back of the hand. The experiments are being funded by NASA, the National Institute of Diabetes and Digestive and Kidney Diseases, and Inverness Medical Technology.
Dr. Gerard L. Cote of Texas A&M University and his colleague Michael V. Pishko of Pennsylvania State University are developing a sensor that would be implanted just under a patient's skin. The implant would consist of tiny beads or a thin slab of material that would glow under fluorescent light to varying degrees depending on the glucose concentration between skin cells.
In this method, a person would, theoretically, get the implant at a doctor's office. Then he or she could shine fluorescent light from a device about the size of a laser pointer on the skin over the implant. The device could read the resulting level of fluorescence and provide a blood glucose reading.
Tests in rats have shown the implants did not produce inflammation in the animals or irritate them in any apparent way, and that the beads did fluoresce under the skin under fluorescent light.
A sheet of the material would probably be most practical for human use, Cote noted, as it would be easier to remove and provide a larger area for readings. He predicts such an implant could probably last a year in the body.
He predicted that human tests of the material could begin in 5 years. "A lot of it depends on funding," he added.
Dr. Vladimir Alexeev of the University of Pittsburgh and colleagues are developing a material that, they hope, could be used as an eye insert or contact lens that would monitor glucose levels in the tear fluid covering the eye. The material, called a hydrogel, changes color as glucose levels increase and decrease.
Alexeev and colleagues are now working on their third generation of the material, which shows a shift from red to blue as glucose levels rise. Alexeev's team has received an NIH grant to begin animal studies of the material.
