The chicken salad at Toy Story Pizza Planet was delicious and you get the dressing on the side, whatever kind you choose (they are in the section near the counter with the other condiments). It had fresh veggies, chicken and cantaloupe in it. As far as I know all the CS places (or almost all of them) have an entree salad option.
For desserts you have the option of getting fruit. You could also get yogurt and I did this once. It was the light yogurt without any added sugar in it. Many CS restaurants also carry a sugar-free brownie or other item for dessert as an option.
For snacks there is always fresh fruit. It is delicious. I had some grapes one time and they were very good.
For TS meals, many places have sugar-free ice cream as a dessert. For the meals it might be harder. Again, there are always salads available. Grilled items like steak, chicken, etc. Or ask and maybe the chef can create something for you.
I would call in advance for any TS places. My dad is diabetic and if they come with us in 2010 this is exactly what we will be doing. I will call and ask them to put something on our ADR indicating he is diabetic. From what people here report, the restaurants are very accommodating.
Oh and at breakfast buffets they always have hot and cold cereals available, fresh fruits too.