Sneaky glucose molecules elude scientists
According to Dr. Rice, no truly noninvasive glucose-measuring technique has worked so far.
The challenge, he said, is that it’s difficult to measure tiny glucose molecules, which have no color and share many characteristics with H2O.
“The real problem is trying to measure a colorless molecule in a sea of water,” Dr. Rice said.
Glucose lab tests rely on indicators from reactions with other substances, he said, “but you can’t do that in the body.” Measuring glucose in tears or urine is one possibility, he said, but the scarcity in those liquids poses a challenge: “Your body doesn’t want to spill glucose and lose energy.”
Dr. Rice himself explored a glucose-measuring technique that aimed to correlate glucose levels to the speed of the retina’s reaction to light. The idea was that patients would wear special glasses that would shine a light in the eye at the press of a button. The project ultimately failed.
There are other challenges, said Dr. Baers, the technology adviser. “Glucose concentrations in sweat or tears are not reflective of blood glucose concentrations. To make things even more challenging, glucose levels in these fluids are orders of magnitude smaller than that found in blood.”
And, she said, there’s a time lag between glucose levels in blood and in other body fluids. “This means that a sweat glucose level is really giving information from an hour previous, which can be dangerous if you’re operating machinery or driving.”