Continuous glucose monitoring doesn't require a blood draw, but it isn't in a form that would work in a watch to my knowledge.

I expect that Apple and others are heavily invested in cracking glucose monitoring on a watch like this. That unlocks a lot of possibilities for diabetics and non-diabetics alike.

Levels is probably the closest thing to this right now: https://www.levelshealth.com/ - There are other continuous glucose monitors, but the "smart" integrations with fitness tracking, etc. seem novel to me.

Freestyle Libre is a device you attach and replace every seven days. It can be read by a hand held patients get but there are apps for some features. Even it can be off and living with one you get used to where its going to be relative your actual level.

So I doubt they will get far from that any time soon. The first company that can do it without puncturing the skin is going to have one helluva a market. How that is done, if that can be done, is still to be seen. Perhaps there is some other measurement not yet considered which can offer numbers.

There are teams/companies working on this and I believe the sensor patches are available, not aware of anyone making a wearable computer out of it (yet):

https://sciencebeta.com/transdermal-glucose-measurement-patc...

Verily (Google) tried contact lenses, but couldn't get it to work: https://blog.verily.com/2018/11/update-on-our-smart-lens-pro...

Possibly with an implant?