I'm Type II on Metformin and Glucophage. Been vaping slightly over 1 month now, with no observed impact on my blood sugar as a result of vaping.
I did have an issue with increased blood sugar (not dangerously, just noticeably) from eating more... the taste buds started waking back up.
But... I've vaped PG and PG/VG mixes with no noticeable change.
This is anecdotal, and limited to me. Offered for informational purposes only. And other standard disclaimers.