For people with diabetes, measuring blood sugar levels can still be painful and inconvenient. Two of the primary contemporary options are finger-pricking or using a needle inserted under the skin to measure the amount of glucose (a type of sugar) in the subcutaneous fluid. Dr. Jang-Ung Park and his colleagues at Ulsan National Institute of Science and Technology (UNIST) in South Korea are now in the process of testing a contact lens that offers continuous glucose monitoring (CGM) and so could provide pain-free and fairly convenient testing to diabetics.
The bodies of individuals with diabetes have difficulty regulating glucose levels. This is primarily because they do not make enough insulin or cannot use it in the typical way, which is to help our bodies use or store glucose for energy. If glucose levels get too high, diabetics experience hyperglycemia (high blood sugar). Over time, hyperglycemia can be dangerous and damage the eyes, kidneys, heart and nerves. Diabetics have to monitor their glucose levels, maintain a healthy diet and sometimes give themselves shots of insulin. More than 30 million Americans have some kind of diabetes.
The new lens is made of a flexible, silicone elastomer (elastic polymer), inside which a glucose sensor is embedded. The sensor emits an electrical signal to an LED light – if the glucose rises above a preset level, the light turns off. This lets the person know that their blood sugar levels are too high. The lens and components are see-through and so do not impair vision.
“[We] report an unconventional approach for the fabrication of a soft, smart contact lens in which glucose sensors, wireless power transfer circuits, and display pixels to visualize sensing signals in real time are fully integrated using transparent and stretchable nanostructures,” the study abstract states in the journal Science Advances in January 2018. The scientists have tested the lens using artificial tears with added sugar and also in trials with rabbits. The lenses were applied to the rabbits’ eyes and with the introduction of a glucose solution into the eyes, the light turned off, as designed.
Whether and how well the device will work on humans is yet to be seen, but the researchers tell The Verge they are in the process of setting up clinical trials with a hospital. There is some doubt as to whether tear glucose levels match blood glucose levels closely enough to be a safe alternative. “It’s an unreliable measure of blood glucose. And that’s something you have to measure with great reliability or you will expose people to harm,” John L. Smith, former chief scientific officer of Johnson & Johnson’s glucose monitoring division, coveys to The Verge. About 75 percent of Americans use some sort of vision correction. It is unclear at this point how well this glucose-measuring device would integrate with standard lenses or glasses.
Despite current uncertainties regarding this type of device’s application, Google has been developing a smart contact lens for diabetics since 2014. Also, in 2017, a thin, skin-like biosensor that offers needle-free blood sugar testing was reported in Science Advances. This device, still in development, requires a new battery and biosensor for each reading, so is not yet considered continuous.