US tech giant Google says it's testing a smart contact lens to allow diabetics to measure and monitor glucose levels in tears. Prototypes using a tiny wireless chip and miniaturized glucose sensor embedded between two layers of soft contact lens material have provided glucose readings once per second, Google reported on a company blog Thursday. Since glucose levels change frequently with normal activity like exercising, eating or even sweating, with sudden spikes or precipitous drops dangerous and not uncommon, the contacts could offer an easy way for round-the-clock monitoring, project co-founders Brian Otis and Babak Parviz said on the blog. They're exploring the possibility of integrating tiny LED lights that could light up to inform the wearer if glucose levels have crossed above or below certain thresholds, they said. "It's still early days for this technology, but we've completed multiple clinical research studies which are helping to refine our prototype," Otis and Parvis blogged. "We hope this could someday lead to a new way for people with diabetes to manage their disease."