Fair warning of the lengthy post to come, Ron. (That
is your first name, right?)
So here goes ...
Re: Your multi-cat household - You're in a tough spot, feeding-wise; I feel for you. You have 1 diabetic kitty + other non-diabetic cats, all of whom are accustomed to grazing (which how I used to feed Bat-Bat, pre-diabetes; most people feed pets this way).
Getting a kitty’s blood glucose #s under control requires both insulin AND diet controls.
There are two parts to this problem:

1) Multi-cat household.
2) For someone with a recently diagnosed cat, if you’re feeding “on demand” or in mini-meals, it’s very hard for you to determine where his nadirs might be, on-insulin. (Plus snacks. And possibly also due to your diabetic cat scarfing a little of the other cats’ food unless you are watching like a hawk the entire time they're all eating - which is almost impossible to do ALL of the time ...) Because every time he eats, his blood sugar will rise - so how do you uncover nadir with a cycle full of mini-meals?
The solution that follows will likely not be very popular to most anybody, especially anyone in a multi-cat household. (How do you all manage it?) But it’s the best I can come up with, and is offered sincerely --- & with sympathy for the difficulties of feeding when you have multiple cats.
The way I can see it might happen for your sugar-cat is ... ALL of your cats transition (can’t be done overnight!) to a “non-grazing” feeding schedule (preferably twice-a-day meals, if at all possible) -
at least for now &
especially because the current feeding schedule of all the cats is keeping you from getting your sugar-cat’s diabetes well-controlled.
This would mean you have to take a hard line, toughen up & be the “alpha cat-mom” to your pride o’ kitties.
Keep this in mind: In the wild, cats will characteristically eat a BIG meal, then not eat for an entire day! Our “domesticated” cats have learned to become grazers because we humans turn them into grazers - they would not normally eat this way otherwise. (Remember, I’d done that myself to Bat-Bat - which is how she ballooned up to 18 pounds before the diabetes hit her & whittled her down to skinny by the time she was first diagnosed.) So once we’ve turned them into grazers, it’s only natural for them to heartily pitch a fit (read: buy lots of earplugs
) until we transition them out of that not-so-helpful habit of grazing throughout the day.
It’s hard. You have to stand firm while all those adorable kitty-faces whine & pout & cry & yowl pitifully to try to convince you that they are just STARVING
. (Some may even go as far as to pull a little “hunger strike” - not unlike a bratty 4-year-old who threatens, “I’ll hold my breath until I TURN BLUE!!!” Ha, my daughter tried that once, and found she didn’t win the game. No, it wasn't about food.)
Guess what? Your kitties won’t actually starve.
(Ask Bat-Bat, who for a while sounded like an entire Mormon Tabernacle Choir of kitties as we were making the transition to twice a day feedings. She was a master terrorist, but I didn’t give in.)
She’s still alive & well today.
Will they like it? H*ll, no!
(Why no "furious kitty" emoticon to insert here?) But here’s the deal: You have a sick kitty on your hands. Changing his feeding schedule won’t kill him ... but uncontrolled diabetes can.
How might you manage it?
Well ... it’s you who will have to decide how quickly you can best transition from multi-meals to fewer meals. If they’ve been eating, say, 5 times a day, maybe shift it to 4 times for a few days, then 3 for a few days, then 2. (And no snacks in between.) But here’s the foundation to help you get Rupert’s #’s to come down & stay down:
1) Your diabetic cat eats in a room BY HIMSELF closed off from the others at mealtimes. He get the correct amount of food for his optimum weight and no more than that (unless you’re dealing with hypo event, of course).
2) Any slow-eaters in the non-diabetic bunch stay in another closed room until they finish their respective meals. (Give them a reasonable time limit, hen pick up the food if they’ve not finished. And don’t give it back: they just have to wait until the next mealtime to eat again. Believe me, those two will learn to quit dawdling.)
3) If you have other (fast-eating) non-diabetic cats, they can eat wherever they wants, so long as they’re not with your sugar-cat while eating.
What to do about the large meal/ scarf & barf problem that can occur with 2 large meals per day? (Yep, we went through that messy bit, too!
)
1) As you’re transitioning, the AMPS/PMPS meals gets gradually larger, and any other meals in between get gradually smaller.
2) If you can make it down to 2 (large) meals/day, add water to the food (slows them down) AND pick up the plate for a short “food rest” halfway through the meal. (Essential for Rupert, maybe not so much for the others ... unless you actually get a kick out of cleaning up cat-barf. I am now an expert cat-barf cleaner-upper.)
You will find, over time, that without so many meals/ snacks throughout the day, your sugar-cat will (generally) be ready to eat, pre-shot. And perhaps if you can get all cats in your house on board, your life will feel saner/less stressful, given that you’re now actively treating a diabetic.
Will you run into an occasional snag? Sure! Bat-Bat recently barfed her ENTIRE meal, right after one of her “as needed” insulin shots. arghhanic time!) So first, I reminded myself to breathe. I waited 15 minutes & fed her 1/3 of the usual ration. (TG, it stayed there.) Then 10 minutes later, fed the 2nd 1/3; and in 10 more min. fed the final 1/3. It all stayed down. Checked her BG - it was going up. Checked again at nadir-time to reassure myself. All was ok; crisis averted.
Once you have made the transition & are able to get a clearer picture of when your cat nadirs, things get a lot easier. A couple examples: If he drops too low @ nadir, you give a little higher-carb something & test in 15 min. to make sure that # is rising; if his nadir # is too high after a few cycles at the same dose, you’ll likely need to bump up the dose.
I did not start giving Bat-Bat mini-meals until her pre-shot numbers were starting to average around 150 (or less) at a micro-dose of ProZinc. (She eats at around 6:45 am, 11 am, 6:45 pm and 10:30 pm., with the AMPS/PMPS meals being slightly larger than the other two.) If she actually makes it into remission, I will likely transition her - gradually - to 3 meals/day, then 2 meals/day, because I’d like to have my life back one of these days.
It isn’t an easy task to accomplish, I know: This type of plan may not be workable for you at all (maybe you can only get down to 3 meals/day, for example). And when there are other health complications, too - like pancreatitis, CKD, etc. - you must do what works best to treat all of those conditions simultaneously.
Barring such complications, while I realize that every diabetic cat is different, diabetes is always the same for every cat: It sickens. It emaciates. It weakens. And it can kill.
So do your best; discover what works for you and your kitty. (Take what you need from the above, and leave the rest.)
I will leave you today with the little line that is in a frame above my desk:
“The greatest pleasure in life is doing what others say can’t be done.”
) 
