(Bloomberg) -- Alphabet Inc.’s experimental medical technology unit Verily halted one of its longest-running projects on Friday: the development of a contact lens that measures glucose levels of people with diabetes.

The failure was a mix of technology and biology, Verily said in a blog post announcing the program’s closure. The company couldn’t get the experimental lens, which measures glucose in tears, to deliver assessments of blood glucose with enough consistency to be used as a medical device. Verily had partnered with Novartis AG’s Alcon unit on the project.

“There was insufficient consistency in our measurements of the correlation between tear glucose and blood glucose concentrations to support the requirements of a medical device,” Verily said in the post. “We are at a point where we have decided, together with Alcon, to put the glucose-sensing lens work on hold.”

Accurately measuring blood glucose is critical for diabetics, who use it to calculate insulin doses that keep them alive. Verily said it was still working on other glucose-measuring devices, including a miniaturized monitor it’s developing with DexCom Inc.

Verily said it plans to continue developing other eye-related technology. That includes a contact lens for people with presbyopia, which is the gradual loss of ability to focus on nearby objects, and an intraocular lens to help improve sight after cataract surgery.

To contact the reporter on this story: Kristen V. Brown in San Francisco at kbrown340@bloomberg.net

To contact the editors responsible for this story: Drew Armstrong at darmstrong17@bloomberg.net, Alistair Barr

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