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To measure blood sugar level without the need to prick fingers, South Korean researchers have developed a glucose monitor embedded in a soft contact lens. It measures the blood sugar level in tears and sends the information wirelessly to a handheld device, LiveScience reported.
The developers reckoned that the device will be available commercially for human use in five years. So far, the gadget has been tested successfully in rabbits which showed no sign of discomfort.
Only one eye
The contact lens will be placed in one eye only. Unlike traditional contact lenses, it will not be used to correct vision.
Advances in material sciences and nanotechnology have enabled the team, led by Jang-Ung Park, a professor of engineering at the Ulsan National Institute of Science & Technology in South Korea, to design flexible or stretchable structures and circuits. The device includes an LED display embedded in the lens.
It is not the first attempt by scientists to develop a glucose monitor using contact lens. But past tries encountered difficulties because of too brittle electronics and too rigid lenses. The gadget previously developed was uncomfortable and prone to breaking. It also blocked vision and could potentially damage the eye.
Park said his contact lens uses a soft lens with stretchable electronics and displays. It can be turned over and the LED light can be emitted into the eye of the wearer or in the opposite direction, depending on the choice of the user.
It will measure glucose levels in real time in natural tear secretions. The data will be relayed through the LED display that can emit a non-intrusive light if the blood sugar levels become too high. The lens will have a miniature antenna to transmit information wirelessly.
Not as accurate as finger prick
However, even if techniques have been available for years to measure blood sugar level in tears, the blood sample from a finger prick is still the benchmark when it comes to accurate glucose level measurements. Among the reasons why tears are less accurate is that glucose concentrations can go down if the eyes are more watery from crying or allergies.
Matt Petersen, the managing director of medical information for the American Diabetes Association, confirmed that tear glucose levels vary in relation to blood glucose levels. He said much research still needs to be done to clarify the correlation and how closely tear glucose levels track with blood glucose levels.
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The Verge also cited John Smith, the former chief scientific officer of the glucose monitoring division of Johnson & Johnson, who was impressed by the circuitry on a flexible contact lens. However, like Petersen, he also was wary of the unreliable measure of blood glucose by the device which must be measured with great reliability or expose people to harm.
But the contact lens device may serve as a convenient proxy to glucose measurements because it is done continually in real time. It would compensate for inconsistencies in sampling, the developers said. They are working with a hospital to begin clinical trials of the new device on humans.
Unpleasant way of measuring
There are more than 30 million diabetic Americans who need to constantly monitor their blood sugar levels. The two main methods involve drawing blood by pricking a finger or inserting a needle under the skin which is both unpleasant and invasive. This is the reason why companies have been developing a needle-less glucose monitor for decades. Many, including Google, have tried but have yet to succeed.
Four years ago, Verily Life Sciences, a Google spinoff, tried to develop futuristic devices that could track glucose levels or detect cancer. However, the San Francisco-based company used opaque and rigid electronics embedded into hard contact lens which was uncomfortable to the user, and the blood sugar measurements were likewise not reliable, Sciencemag noted.
Diabetes is also prevalent in South Korea which led Park to develop the contact lens that can measure blood sugar levels. According to data from the Korean National Health Insurance Service, the diabetes rate increased to eight percent in 2013 from 5.6 percent in 2006.
Park said that not all the components of the device are flexible. For instance, the glucose sensor has two rigid pads of silicon, but to make the overall lens flexible, they placed the rigid parts on ultrathin islands for support and connected it with a web of flexible wires so thin that it is invisible to the wearer. It allows the connected islands to move and stretch independently and make the lens, in theory, more comfortable.
The electronic components are only 1/100 the thickness of the soft contact into which it is incorporated that the user would not notice it, Park explained.
But David Walt, a diagnostics expert at the Wyss Institute of Harvard University in Boston, pointed out that Park must address one issue. It is the reliance of the glucose sensor on an enzyme, glucose oxidase, to bind to the sugar and measure its levels. He noted that the binding generates hydrogen peroxide, a reactive compound which can damage the eye.
[메디컬리포트=Vittorio Hernandez 기자]