I just posted on another thread. I've been a T2 food-controlled diabetic for 40 years. That means I take no diabetic meds that would change my readings. I have seen absolutely no changes in my readings vaping. VG, in fact, is a staple doing my own baking. I use it to keep cakes, cookies, breads, etc moist. Most diabetic commericial baked goods contain it. As for flavorings, I use those too in food. They contain zero carbs in any form. Only the bioflavinoids are are extracted from fruits... not carbs/sugars. Sugars, in fact, will not work with an atty that's exactly why "sweet" juices usually contain ethyl maltitol (sp?) as a sweetener or use sucralose (popularly branded Splenda) and no sugar. I use those in both my food and vaping.
PS... and JMHO... one must watch for anti-vaping "plants" on the forums. In my view, vaping is an AID for a diabetic. I could never eat some of the lucious desserts juices are patterned after but I can enjoy the taste of them vaping! *tiramisul here I come*