Could a device worn on the surface of the eye let people with diabetes monitor their blood sugar? Google [x], the semi-secret lab behind Google Glass, is developing a contact lens that measures glucose in tears to deliver an accurate blood sugar reading.

"We wondered if miniaturized electronics—think: chips and sensors so small they look like bits of glitter, and an antenna thinner than a human hair—might be a way to crack the mystery of tear glucose and measure it with greater accuracy," wrote project co-founders Brian Otis and Babak Parviz in a Google[x] blog post.

Early in 2014, Google [x] revealed a functional prototype of this smart lens, which uses a tiny wireless computer chip and a miniature glucose sensor that are sandwiched between two layers of soft contact lens material. Once the glucose is detected, the information can be sent to a smart phone or another device.

What Doctors Have to Say About the Device

"At this point in time, it is a way down the road," says Leann Olansky, MD, an endocrinologist at the Cleveland Clinic. "One question to be answered is timing. If the lens gives a reading of what the blood sugar was an hour ago, it would not be that useful, but if it could tell what the blood sugar was 10 minutes ago, it could be worthwhile."

One possible problem with the little device is that the glucose found in tears may not accurately reflect an individual's blood sugar, says Mark Fromer, MD, an eye surgeon at Lenox Hill Hospital in New York City. "Tears are right on the surface of the eye," he explains. "But the Google lens does not have access to the aqueous fluid inside the eye. What we need to find out is how quickly the glucose levels in the tear film will change based on the patient's blood sugar level."

In order for the test to be useful, Fromer explains, the tear glucose level must accurately reflect the current blood glucose level. "If they can accomplish this, the device may prove to be very useful."

According to the blog post quoted above, Google [x] has already conducted clinical research studies and discussed the device with the FDA, but the technology is still in its early stages.

"We've always said that we'd seek out projects that seem a bit speculative or strange," write Otis and Parviz. "And at a time when the International Diabetes Federation (PDF) is declaring that the world is 'losing the battle' against diabetes, we thought this project was worth a shot."

Mark Fromer, MD, reviewed this article.


  1. James, Susan Donaldson."Google contact lens to monitor diabetes holds promise, say doctors." 17 January 2014. ABC
  2. "Introducing our smart contact lens project." Google.