The New Scientist explains:
Contact lenses that change their appearance according to the wearer’s blood-sugar level could one day help people with diabetes keep track of their levels non-invasively, new research suggests.
But Chris Geddes, the study’s lead author and associate director of the Center for Fluorescence Spectroscopy at the University of Maryland, US, has tried to create less painful alternatives. Developing a monitoring system through contact lenses makes sense because many people with diabetes also need glasses or contact lenses due to the way diabetes affects the blood vessels in the retina, Geddes says.
To make glucose-sensing contacts, scientists added boronic acid to disposable contact lenses. Moisture from the tear ducts contains glucose that binds with the molecules of boronic acid, with the reaction causing fluorescence. A handheld device flashes a blue light into the eye and measures the intensity of the resulting glow, letting the user know their blood glucose level.