Read In Defense of Food by Micheal Pollan. There's a bit in there on diabetes research done on an aborigine population. The big point is that escaping from the American diet is essential. Like you say, a mostly vegetarian diet or a diet based on traditional food sources, small scale agriculture and hunting and gathering. Don't try and hang on to this lifestyle by replacing crappy processed food with crappy processed food for diabetics. It sounds like thats kind of the path you're on now. Good luck, its a tough row to sow.