I'm actually part of a research team working on using a wrist mounted spectrometer to actually measure glucose continuously and non-invasively. Turns out it's a really really hard problem.
Do you mind sharing who the team is? Do they have any literature available?
https://investors.rockleyphotonics.com/news/news-details/202...
There was a press release last year because they're an Apple partner. I have high hopes but I keep remembering that Theranos had a lot of promise too.