Well, naturally the overwhelming majority of people who post here would say "please don't PTS just because of diabetes, because diabetes is not a death sentence". And I think we all truly believe that to be true. And simple diabetes isn't a death sentence provided it can be managed. But none of us is in your shoes, so it really isn't fair for any of us to judge.
I went back and read your prior posts from a couple weeks ago.
You have six kitties? And are moving or have just moved?
You mentioned that you were feeding a raw diet.
And that you were planning on purchasing a test kit.
But I didn't see you mention what type of insulin you are using.
Of course, we would like to help you to help your kitty. From previous blood tests or any tests, are there other complications besides diabetes involved? Are you trying to treat multiple conditions?
Bottom line, and just my opinion...
Only you can make this decision, and I get the sense that it isn't a decision you are taking lightly at all. If given a choice between PTS and doing nothing to treat the illness (like no insulin, for instance), then putting the cat to sleep would be the better choice. But have you considered maybe trying to find a new home for him, where someone would be able to treat him? I know that isn't a really likely option, but many of the cats here were adopted because they were diabetic. And organizations like DCIN try to rehome diabetic cats.
None of us would want you to lose your kitty to this illness. But none of us can fully understand your situation either. All we can offer is help if that's an option.
When my cat was first diagnosed, the possibility of putting him down was mentioned. But it was a purely financial question. Ultimately, I refused to do it and elected to spend my savings to treat his DKA episode, then started with insulin, diet change, etc. It took only 10 weeks for Bob to go into remission, so I was extremely fortunate in that aspect. And very glad that "PTS" wasn't our final decision. But it might have been, so I can understand where you are right now.
My hope is that you'll reconsider, but I can't judge you regardless.