The latest glucose-sensing smart contact lens still has a long way to go
The device is the latest attempt to develop a needle-less blood sugar monitor for diabetics. Building the circuitry on a flexible contact lens is impressive, says John L. Smith, former chief scientific officer of Johnson & Johnson’s glucose monitoring division and author of The Pursuit of Noninvasive Glucose: Hunting the Deceitful Turkey. But the glucose readings from tears just don’t reflect the levels in blood reliably enough to guide treatment decisions for people with diabetes, he says. “It’s an unreliable measure of blood glucose,” Smith says. “And that’s something you have to measure with great reliability or you will expose people to harm.”
Smith says that the levels of glucose in tears just don’t track closely enough with levels of glucose in the blood to be used for monitoring. A paper from the 1980s backs that up: after testing 100 patients, “no significant correlation was found between the glucose level of blood and tears,” the study reports. “This is a very, very difficult problem,” Smith says. The team behind today’s study is working with a hospital to start clinical trials, according to an emailed statement. But until we know more about how well this new contact lens works in humans, the quest for a needle-less glucose monitor continues.