I can't imagine the sickly, sugar-shocked boat I'd be in if I wasn't vegan... Diabetes runs in my family and my mom and sister are both very near diabetic (in fact, my sister suffered with pretty severe gestational diabetes while pregnant with my nephew) but neither of them started to develop health problems with it until later on: my sis starting having trouble during pregnancy and since then, mom was OK until around menopause...
I, on the other hand, had been really sick for the past 2-3 years to the point where I accepted it as normal and "everyone probably feels like this everyday"... I put up with it up until a few months ago when I finally decided to see what the heck was wrong with me (constant headaches and vertigo every single day, I was gaining weight like crazy no matter what I did, and didn't have a period for 10 months). Results are still on the inconclusive side, but the general consensus between docs is that I have PCOS due to very high triglyceride levels (or vice versa, you never know with these things).
But the moral of the story is that I've been taking Metformin for a hair over a month now and I've already lost 9lbs, I have not been dizzy or sick before or after eating the whole time, and 4 days into treatment I got my first period in 10 months. Crazy. But yeah... makes me wonder if I'd even be here right now if I wasn't vegan....