Yes, cats can go into remission, unlike dogs and people. We call it diet controlled, because higher carb foods can cause a cat to lose those remission numbers.
Here is an explanation from Marje and Gracie:
"And, finally, I read an article that further supports what Sienne said about the pancreas needing a break. It said when numbers first come down to normal and the beta cells start to heal, they are fragile. Because they are fragile, they can stop working. So I think that the longer a kitty stays in healing numbers, the stronger the beta cells can become until they are ready to take over the job and provide endogenous insulin."
We think the threshold below which the pancreas can "rest" and heal is 250 or so. So the more time spent at those levels, the better.
One thing that seems to help support the pancreas are small, frequent meals. Not more food, just what you are normally feeding split into several meals a day and night. An automatic feeder is wonderful for this as you can set it to go to an empty slot two hours before you want a preshot test. Another way people use is to freeze the food (a silicon muffin pan is great for this) and leave it out to thaw and be eaten over time. (have to say this did not work for Oliver. He dragged the frozen puck all over the house - of course mostly on the carpets- and ate the pieces as they flaked off). We did much better with our feeder, the PetSafe 5.