When you reduce a dose, even temporarily, it can take up to six cycles to build up the depot again.
As cats get towards a better dose, you can start to see some improvement in signs. I'm glad to hear he's more sociable and bit more active, plus not as crazy an appetite. All good indicators.
I would rerun the IGF-1 test and ask if they do the IAA (insulin auto antibodies) test. I don't know of any places other than Michigan State University that run it though. Would love to know if that has changed. I know that IGF-1 tests are more widely available now. I'm curious where they send the blood to be tested from South America.
How long has it been since he's had a basic senior panel blood work and urinalysis?