From your last post you asked:
First of all, symogyi is a not a thing. It's a hot button item here, but a cat that started on a reasonable dose, with tight regulation, proper testing, appropriate increases, this doea not exist. This paper proved it:
Rebound hyperglycaemia in diabetic cats.pdf
GuMung is/was on a reasonable sized dose. When you reduce the dose like you did, the depot of the larger dose still influences up to 6 cycles after the reduction. Today is just cycle 4. He didn't look great last time he was on 4 units. You've held the dose the required number of cycles or more since then and you do a great job testing. Hard to see how you've bypassed a good dose.