You are gonna hate me,

but can please you also add that Blue has a history of DKA to your signature as that is info we definitely need to be aware of should you need/want any assistance with dosing going forward.
I wait till the FF is on sale at PetSmart and buy cases of 24. They often have it on for 57 cents a can but it's possible the sale prices are different in ALTA than in ON.
I have the utmost respect for vets and think they have one of the hardest jobs on the planet but they often don't seem to completely understand how insulin works or they just haven't dealt with enough feline diabetics and tend to treat them like their canine patients. The amount of training vets get on diabetes is limited given most are general practitioners who not only need to know about a lot of conditions but also a number of different species. If they only have one or two diabetic cats at any one time in their practice, they don't have a lot of hands on experience upon which to draw. Nor are they going to spend a lot of time making sure they are up to date on the latest treatment recommendations. To make matters even more complicated, the vet can feel they HAVE to take control of the situation because they are expected to and are therefore reluctant to allow the caregiver more leeway to make decisions for themselves and their kitties. Diabetes is a 24/7 proposition. That doesn't mean you have to spend all your time on your cat but it does mean you need to be prepared for what is going on with your cat 24/7 and most vets are not available 24/7 for immediate decision making for all their patients.
Did your vet recommend testing for ketones at home? With a history of ketones, this is something we would recommend you do on a daily basis to ensure that if ketones were to recur, you can catch the problem quickly and avoid a recurrence of DKA. Testing can be done with KetoStix available at the local pharmacy. You only need a few drops of urine and depending on how private your kitty is about his bathroom habits, some folks can hold a designated ladle under kitties butt while in the litter box to catch a sample. Others can put plastic wrap into the litter box to catch a small sample. Obviously with 2 kitties in the house, that is a bit problematic as you wouldn't know whose pee you were testing. The other solution is to get a glucometer that will test for ketones. There are several on the market and it never hurts to have a backup glucometer around anyway.
If your vet did not advise you to check for ketones at home, this is just one example of where vets often choose not to overburden their human clients with information or suggest they take more control of the situation, for fear they will give up on their furry pets and not want to treat at all.
The dose of insulin Blue is on now is quite high and while he may need the higher dose, it's impossible to tell without some mid cycle testing. Did your vet suggest testing mid cycle when possible to see how low the dose is currently taking Blue's BG.
Just food for thought.
Please come join us over on Health. I'm sure we can help you get Blue feeling better in the very near future.