There might be something to this. I experimented with apple cider vinegar myself a couple of weeks ago, but for another reason. I had a bit of gallbladder trouble going on, nothing severe, but enough so that it got my attention. (Apparently it is not unusual to experience gallbladder 'colic' after going on a diet of any kind, who knew?)
Anyway, while surfing around the net I came across an old post in this forum, wish I had saved it because I can't find it now. The discussion was about relieving gallbladder attack pain, and this person said that drinking 2 TBSP of apple cider vinegar in a glass of water really stopped the pain quickly. He said he used to use apple juice until he got diabetes, so now he used the vinegar as there is no sugar in it. Next time I felt some gallbladder trouble starting up, I tried it - and it worked! Of course I have no way of knowing positively that it did, but the pain lessened pretty fast and I did not progress into total misery.
I didn't think to check this against my blood sugar but now I am thinking that a glass of the lovely mixture might be beneficial to both my gallbladder (still a little pesky) and my BG. Thanks to your post, by the way! I will let you know if I see this connection. I believe it is the pectin in the apples that create the benefit, according to various gallbladder 'diets' that I have seen. But of course, we can't eat a bunch of apples either, diabetics are surely discriminated against by the fruit gods .....
I didn't find it particularly gross to drink, though. It was sort of pleasant to me, the same as drinking lemon water. Sure, acidic but not terrible. I didn't down it all at once though, I took about 10 minutes to drink it, maybe you should try that approach. And forget downing it in a shot glass undiluted - geez, that can make you choke to death!