Image: University of Pittsburgh

Every day millions of Americans living with diabetes must subject themselves to the painful prick of a fingerstick test to monitor their glucose, or blood sugar, levels. Studies have shown that diabetes complications can be greatly reduced by measuring glucose levels several times a day to inform diet and medication decisions. Yet the discomfort and inconvenience of the fingerprick method mean that many diabetics fail to test themselves as often as they should. A new biotechnological device described in a recent issue of the journal Analytical Chemistry may eventually change that.

University of Pittsburgh researchers Jerome S. Schultz and Ralph Ballerstadt have developed a tiny glucose sensor for implantation just underneath the skin. The sensor is made up of a half-inch-long plastic tube roughly the diameter of a piece of thread (on top of dime in photo), filled with particles that fluoresce according to blood sugar levels. A monitor fitted with a photometer sits on the skin surface directly above the implant, measuring the light intensity, which in turn reflects the glucose concentration.

Unlike fingerstick tests, the implant enables continuous monitoring. Another monitoring system currently under development (although much further along) is GlucoWatch, a noninvasive device that estimates blood sugar levels by analyzing glucose-containing fluids that it extracts through the skin. Currently, this method yields an average of glucose levels over a 20-minute period. The implant, on the other hand, directly samples the glucose concentration in tissues. As a result, Schultz believes his technology "will be able to rapidly reflect the dynamic changes in tissue glucose with a response time of about three to five minutes." Such a rapid response, he says, "could be very important for hypoglycemic [low glucose level] episodes in children, which can cause children to go into shock." He further notes that a "continuous monitor could also be rigged as an alarm to warn parents of possible seizures."

Although the device has not yet been subjected to in vivo studies, Schultz is thinking ahead. He hopes that future research will lead to an even better solution. "The ideal situation would be a completely reliable, portable, fast-working glucose monitor that is attached to an insulin pump--an implanted device that can be programmed to release synthetic insulin in unison with demand."