On the bright side, Yuki (16 year old cat) may be on a honeymoon period where she will not require insulin injections for a while. On the basis of her blood glucose level readings on Friday, her vet thought we should take her off her already very low dose of insulin and do another blood glucose curve on Tuesday and see what her levels are like.
On the bad side, her good blood glucose level readings means that her increased thirst and urination are probably due to the early stages of renal failure. The results of her blood and urine tests suggested that all we should do at this point is change her diet. The choice there would be between appropriate choices of regular commercial foods, prepared prescription diets (probably Science Diet) available through the vet's office, or a home prepared diet. I'll talk to the vet in more detail about it on Tuesday and update you all then.
We lost a cat to kidney failure. He was just so sad that I couldn't be upset when he was finally put down. So I have my fingers crossed for your kitty. I'm so impressed at the commitment and love you show for all your pets. I doubt I'd cope half as well if any of mine got sick.