Unfortunately, at the outset of the treatment, the best you can do is have some nuts and wait for it to go away, which usually takes about 15 minutes or so. Generally, most people can tell before they come on that they're coming, and it's good to eat nuts at this point. I myself have never had a severe attack since being on my diet, only minor ones, which I simply had to do my best to ignore or eat nuts if I found them worse than usual. It wasn't easy, but I really can't offer more than that. If you can handle grain you can try something like that, or maybe a small amount of fruit. That should not be a habit though, nuts are the best. For a very severe attack, if it ever happens, it may be necessary to have some diluted juice.

Can coffee cause an attack?

OH YEAH. Caffeine in ANY form causes your liver to release it's glycogen stores, which in turns raises your blood sugar. This is the 'waking' effect people experience when they drink coffee 'to get going in the morning.' It's not the caffeine, it's the sugar rush caused by it that 'wakes you up.'

So why does it cause an attack? Isn't hypoglycemia when you have low blood sugar? So wouldn't the sugar rush be good for you?

It would, but the problem is that your pancreas is already shooting out too much insulin because of how you've been eating. It interprets the sugar rush as a danger and goes back into the same mode it's been in that was causing you to get sick in the first place.