The good news is that it's not feline diabetes.
The bad news is that there still isn't any bad news.
After finding a small amount of white blood cells in his urine, the vet has started him on a course of antibiotics on the chance it's a kidney infection. So now it's two pills a day, but luckily he's usually too startled to notice and I don't even need to use the piller.
Additional tests have been sent for, but no word yet.