As a diabetic who generally avoids starch/sugar but is chafing a bit at that, this is interesting news. I’ll look some stuff up, but thanks for the one-liner summary.
Just be sure to dilute it with water (or green tea, I guess). Straight vinegar will do a number on your teeth.
Might I suggest rice vinegar? You might have to try a few to find a good one but many are juiuuust sweet enough to take a spoonful straight. But I like rice vinegar and sour stuff.
I’ve seen some stuff about the blunting the glucose spike and what I remember is that there were several acidic liquids tried. Apple cider vinegar, rice vinegar, and lemon or maybe lime juice?
Upshot was that as long as it’s a strong enough acid it works.
I’m a big fan of, possibly even addicted to, the plastic jugs of Starbucks dark roast Iced coffee available at supermarkets. But, I would never consider diluting it with ice. I like mine full strength.
I have a french press too, for whenever I’m in the mood for something hot that is high octane.
You’re just thinking like a modern person who goes to the store and buys things in boxes. For most of our time on earth, we figured things out by tasting them, soaking them, cooking them. We’re experimenters by nature.
However, coffee the drink is a recent experiment, in Ethiopia around 850 CE or thereabouts. Probably roasting and eating the beans came first.
Well, I didn’t think about it that way. Point taken. 
That is to say, I didn’t think about it the way you subsequently explained it.
Pollutants? 
A suggestion for a good brew: go to coffeebros.com and order a bag of their Ethiopian beans (scored 92 points by Coffee Review). It’s really good coffee and fairly expensive, but a nice cuppa. I’m waiting on my 2lb bag order to show up today. It ran me over $60, but I only drink a cup a day, so it lasts me quite awhile. I make it stretch by switching off with my pinon coffee from New Mexico, which I also highly recommend.
I buy the cheapest whole beans at Costco. Serves me just fine.
I don’t blame you. I was buying bulk for a long time, but at my age I feel I can treat myself.
But there really and truly is a difference between different beans and different qualities and freshness thereof. I can barely tolerate most grocery store coffee beans. The stuff I used to buy was a particular Guatemalan bean freshly roasted right in the store, but now that supermarkets are allowed to carry wines and mixed drinks, that place devoted such a vast amount of space to booze that their coffee selection is much more limited, and I can’t find the Guatemalan stuff any more.
I’ve had to go by their descriptions of their limited supply, and the one I finally picked as suitable is OK – not as rich and flavourful – but most of all, weaker, so I have to increase the coffee quantity over what I used to use.
The coffee one uses also has to match the coffee-making method, not just the grind, but the actual bean. They all produce different results.
But hey, Costco has good stuff, and if their cheapest bean works for you, great! 
One of my favorite novels is The Coffee Trader by David Liss. Set in the mid 1600’s in Amsterdam and follows the introduction of Coffee to Europe from the West Indies. Very good historical fiction,
