Google has unveiled a contact lens that monitors glucose levels in tears, a potential reprieve for millions of diabetics who have to jab their fingers to draw their own blood as many as 10 times a day. The prototype, which Google says will take at least five years to reach consumers, is one of several medical devices being designed by companies to make glucose monitoring for diabetic patients more convenient and less invasive than the traditional finger pricks. The lenses use a minuscule glucose sensor and a wireless transmitter to help those among the world's 382 million diabetics who need insulin to keep a close watch on their blood sugar and adjust their dose. The contact lenses were developed during the past 18 months in the clandestine Google X lab that also came up with a driverless car, Google's Web-surfing eyeglasses and Project Loon, a network of large balloons designed to beam the internet to unwired places. But research on the contact lenses began several years earlier at the University of Washington, where scientists worked under National Science Foundation funding. Until Thursday their work had been kept under wraps. "You can take it to a certain level in an academic setting, but at Google we were given the latitude to invest in this project," said one of the lead researchers, Brian Otis. "The beautiful thing is we're leveraging all of the innovation in the semiconductor industry that was aimed at making cellphones smaller and more powerful." American Diabetes Association board chair Dwight Holing said he's gratified that creative scientists are searching for solutions for people with diabetes but warned that the device must provide accurate and timely information. "People with diabetes base very important health care decisions on the data we get from our monitors," he said. The device looked like a typical contact lens when Otis held one on his index finger. On closer examination, sandwiched in the lens are two twinkling glitter-specks loaded with tens of thousands of miniaturised transistors. It's ringed with a hair-thin antenna. "It doesn't look like much, but it was a crazy amount of work to get everything so very small," Otis said, at Google's Silicon Valley headquarters. It took years of soldering hair-thin wires to miniaturise electronics, essentially building tiny chips from scratch, to make what Otis said is the smallest wireless glucose sensor ever made. Other non-needle glucose monitoring systems are also in the works, including a similar contact lens by Netherlands-based NovioSense, a minuscule, flexible spring that is tucked under an eyelid. Israel-based OrSense has already tested a thumb cuff, and there have been early designs for tattoos and saliva sensors. Palo Alto Medical Foundation endocrinologist Dr Larry Levin said it was remarkable and important that a tech firm like Google is getting into the medical field, and that he'd like to be able to offer his patients a pain-free alternative from either pricking their fingers or living with a thick needle embedded in their stomach for constant monitoring. "Google, they're innovative, they are up on new technologies, and also we have to be honest here, the driving force is money," he said. Karen Rose Tank, who left her career as an economist to be a health and wellness coach after her Type 1 diabetes diagnosis 18 years ago, is encouraged that new glucose monitoring methods may be on the horizon. "It's really exciting that some of the big tech companies are getting into this market," she said. "They bring so much ingenuity; they're able to look outside the box."