Would a treat of chicken be ok after testing? That's when I usually give him a spoon of FF so whenever I sit in the 'testing chair' he comes. I'd hate for that to change.
Well ... I would really avoid that, for now: Try a scritch under the chin or a nice cuddle as a reward instead. Remember: You're treating an illness here, not rewarding Colin for cleaning up his room.
(Again, I
know how hard this is to do; please don't think that I am unsympathetic toward you & your kitty.)
Try to keep thinking along these lines in your efforts to get Colin better regulated: The food is "medicine," too, or even anti-medicine if administered incorrectly (i.e., wrong amounts/ wrong type/ wrong timing, etc.)
You say Colin is a big cat, that he weighed 18 lbs before diabetes - but I think we can safely assume that 18 lbs means he was an obese kitty back then.
As for his current 13 lbs, he
may actually need to drop a little bit more; my vet told me that slender is preferable in a diabetic cat (
not emaciated/skin & bones, like they so often look after diabetes has been eating away at them). Seeing the results for my own cat, I have to say I agree with him on that. I only mention this because my cat used to weigh 18 lbs. and she is a large-frame cat, too. Now she weighs about 11 lbs. I think Colin might be just fine at 12.5 lbs - or maybe, over time, even 12 lbs.
An extra 1/2 pound or so may not sound like/look like much - but on a cat's body? That's actually quite a bit when you're treating diabetes!
Your cat is a male; often we perceive them as naturally being larger than their female counterparts. (Anybody would
think Bat-Bat is a male!) But all things considered, you may actually want to slightly
reduce his rations: By say only 0.25 of a Fancy Feast can, to 2.75 cans FF total per day, divided into the two meals. (You had him on a total of 3 cans per 24 hrs, right?) But it may actually be better for you to wait several days before attempting any type of small redux in rations - thereby allowing Colin's body to adjust to the change in feeding routine
first.
Then you might might try that slight reduction in rations for a week to 10 days; weighing him
daily. (Is never a good idea for a cat to lose even a half-pound
too quickly.)
Keep in mind that - especially with a change in feeding routine - even a gradual/ small food reduction will make it important for you to monitor him closely around nadir time. As shifting the food-insulin balance could result in a significant shift downward in his numbers. (That's what we're ultimately hoping for, right?)
Is up to you, of course, which (if any) of these additional ideas I've offered up that you want to try:
You not only hold the syringe; you also hold the food dish.
Will be thinking good thoughts for you, Sharon - regardless!

- Robin