The glasses have a small sensor positioned on the nose pads, close to the tear duct., and the sensor can then measure the concentration of glucose in tears. Because the level of glucose in tears goes up and down in proportion to the level of glucose in blood, measuring glucose levels in tears provides a reliable approximation of blood glucose levels. The device works once the user has produced tears and they come into contact with the glucose oxidase in the sensor.
The glasses have been developed by teams from the University of São Paulo's São Carlos Physics Institute and the University of California
's Department of Nanoengineering, in San Diego. Lead researcher Laís Canniatti Brazaca, a physician and researcher at the São Carlos Chemistry Institute, said: "The concentrations of various metabolites in tears reflect concurrent blood levels, making them an attractive medium for non-invasive monitoring of physiological parameters."
She said the device could also measure levels of vitamins and alcohol in the blood by "simply changing the coupled electrode attached on the eyeglasses' nose pads."
The team notes that tears need to be produced for the sensor to work. This is possible by exposing the eye to substances that stimulate the lachrymal glands (tear glands). While the concept is certainly different, there's a question of how much of a benefit the glasses would have compared with flash glucose monitors or continuous glucose monitors that do not require tears to be manually stimulated. And if the researchers are to continue developing the glasses, they may need to ensure that the sensor does not present any possibility of accidental eye injury.
The researchers do not have a date for commercialisation.
Source: Diabetes UK
Top image: Juliane R. Sempionatto Moreto / University of California