Sorry to hear the bad news, Dibdib and Madcow. 
Pippin has spent the day at the vets getting fluids, her blood glucose went from 15 to 8 at either end of the day (with more food and no insulin, which is a bit arse about face if you ask me) and steadfastly refusing to provide a urine sample. She's staying in overnight to get more fluids and hopefully home tomorrow some time.
Insulinoma? Over-active tumour on the pancreas that produces excessive amounts of insulin at the slightest provocation. They're common in ferrets, and when we were trying to stabilise Wellesley we would feed him a syringe full of glucose before the normal food to mop up the excess insulin. A combination of steroids and sub-cutaneous testosterone kept him going happily for another many months.
The vet did posit the idea of a pancreatic tumour, but how do you tell in a diabetic cat? Especially one that has the shits constantly and therefore obviously isn't absorbing properly.
Anyway, since I last posted the runny poos haven't cleared up and the vet said last Thursday that he suspected gastrointestinal lymphoma. She's had no insulin for 2 weeks now and had stopped eating when we last went. Last chance saloon was to try steroids, normally contraindicated in diabetic cats but as her BG was normal he gave her a short acting one for a whirl, borrowed time really before she starves.
Appetite came back with a vengeance (can't remember when I last saw her eat so much food), though it has tapered off now, and she seemed to go blind for a couple of days which I'm guessing may have been blood pressure related.
She goes back on Friday for a BG check and we'll see what the vet says then.
We're going on holidays in 3 weeks and I'll never forgive myself if she were to need to be put to sleep with strangers
