Well, I have a sad update. Noel turned out to have other health problems which caused him to not be able to process the insulin properly. He got really sick again and the vet suggested he be put down.
His last couple weeks were spent in a volunteers home so he got lots of love there at the end. She played with him and spent time with him and really got attached. So at least he didn't have to finish out his life in a shelter.
He was a sweetheart.