https://thenextweb.com/syndication/2019/11/30/biosensor-equipped-glasses-could-monitor-diabetes-through-tears/

Brazilian and US scientists have developed a glasses-based biosensor capable of measuring blood glucose levels through a person’s tears, offering a less invasive test for diabetics.

Glucose levels need to be frequently monitored in people with diabetes, a disease that affects 62 million people in the Americas and 380 million worldwide.