I don't know if LB was less itchy without the insulin but his pancreas looks like it needed the support.
I suspect there are a couple of things going on. When you stopped shooting, you stopped at a dose of 0.5u. You needed to hold that dose longer than you did when you restarted. One day was not long enough. You then increased LB's dose twice in one day. All of those back-to-back changes would result in a wonky response in pretty much any cat.
Unfortunately, sometimes when you drop a dose or stop insulin, you may end up needing a higher dose than where you were previously dosing. This sometimes happens even if you've not stopped insulin. For whatever reason, what was an effective dose is no longer enough juice and you have to provide more insulin -- you have to go up higher before your cat's numbers come back down.