Here is a post I made in another related topic, perhaps it will shed some light on this.
rated at 4 calories per gram of PG and 1 gram equals 1 ml (1/1000th) of a liter. It is rapidly metabolized as a sugar does for energy.
Bottom line is in order for it to affect BG levels one would need to ingest several ml in one dose, we inhale several ml over many hours so the raising of BG is moot for the most part, as this only pertains to pure PG minus flavorings but this too is of no concern as the flavorings are inhaled over long periods of time also, even if they have a higher glucose amount.
So for any juice to raise the level of BG one would need to drink a bottle of 10ml or vape the entire 10ml in one inhalation.This would equate to 40 grams of glucose ingested and will vary in the individual diabetic, differing for Types 1 and Type 2 as to how high the BG will raise.
For example if a Type 1 needs 1 unit of insulin per 10 grams of glucose, he/she would inject 4 units to cover the intake of a 10ml bottle of juice.
For Type 2 it is a whole different ballgame as they must rely on their own insulin with the aid of a pill or low dose injection if at all used, but the affect is still the same, very little if any rise in BG would be noticed.
The downside is, that smoking constricts blood flow, as does poor BG management and interferes with metabolism. Vaping does not so improved circulation and metabolism is benefited.
So if you are a diabetic, just not smoking is HUGE and the use of vaping is the tool to keep that benefit and if it does affect BG just monitor how it does and adjust for it.
I have a 5.1 a1c after quitting analogs, prior to that I had a 6.3 a1c....Been Type 1 for over 30 years...I say to diabetics...... fogettaboutit......VAPE ON