When you eat alot of carbs, your insulin goes up! Insulin then interferes with fatty acid metabolism and tends to push products into the inflammatory side of things. (these cytokines are called PGE2's ).

Staying on the PGE1 side of things quells inflammation.

The Zone diet, and the books about them explain how this works.
So even if you are not showing diabetes in glucose tests, you might be having high insulin events, and thus be in the inflammatory condition.

By balancing carbs with protein you control insulin levels, and also stimulate glucagon its opposite partner, to move glucose around in a more stable way for you.

Eating more Omega-3 fats, like Flax oil, and fish oil, moderate and dampen the inflammatory side of our fatty acid chemistries.

Don't forget, inside all of us is a biochemical factory of huge complexity, and food, can alter the balance of this and create many problems. I think the Zone diet is quite diabetes friendly. There have been studies showing good results with type II diabetics. It is possible to do Atkins without animal flesh, but not wholly vegan...because there are alot of carbs in most vegetables. Atkins is a high fat, high protein diet. Tomatoes are not typically allowed, at least in the beginning. One could do the Zone including dairy/eggs, and soy. But some people cannot tolerate high soy either. But I think the Zone is possible for some vegetarians.