“Google was working on (and then cancelled [0]) a contact lens that measured glucose levels in the tears and then communicated those levels with a small LED in the lens itself.”
It's a really hard problem. There are perhaps a dozen experimental noninvasive methods to get a rough approximation of glucose levels, but none that work consistently enough and accurately enough to make insulin dosing decisions. For that you need fingerpricks or a subcutaneous CGM.
I don't think we'll ever have safe CGM that isn't minimally invasive. Proteins are weird and you really need to measure blood, not a picture of blood through skin. We are only recently getting CGMs that don't need frequently recalibrated via a finger stick. I hope someone prove me wrong but it would be quite the leap forward in tech.
“Google was working on (and then cancelled [0]) a contact lens that measured glucose levels in the tears and then communicated those levels with a small LED in the lens itself.”
[0] https://www.labiotech.eu/in-depth/contact-lens-glucose-diabe...