PizzaPizza
Pizza is one of the single-hardest foods to eat with diabetes. The complex mixture of carbohydrates and fat cause my blood sugars to go up, and stay up. I've gotten better at learning how my body digests the stuff, and features like "dual-wave bolusing" from the insulin pump helps a lot.

Interestingly enough, salads are equally difficult. Before I got an insulin pump having a salad for dinner would inevitably result in my blood sugar going too low an hour after I finished eating. There are no carbohydrates in salad, or very few, and it would always react negatively with the insulin I would take. However, with an insulin pump I can simply bolus for specific amounts and everything works wonderfully.