Sorry to take so long getting back to you. Definitely do not give her insulin if she is not eating. The worry is that if her blood glucose levels are not as high as usual and you give her insulin without her having food in her to counter the insulins effect, she could succumb to hypoglycemia (low blood glucose level). forcing a little bit of canned food can help with her blood sugar levels (smearing a little on her paws where she will lick it off or onto the roof of her mouth) as can giving a little corn syrup orally.
A visit to the vet is urgently needed however. There is a small chance she is reverting ack to being non-diabetic, which would be great. Lets hope.
She is NOW refusing water...sorry I typed the wrong word.