The pre shot numbers are best used to know if its safe to give insulin. It's the nadir values that are more important in judging a dose. You want to give a dose that gets him into high double digits or low 100s fairly consistently. I think the 3.25 u dose is close but I'd try 3.5 u soon. The hope is that PSs will gradually come down when middle cycle numbers are in a better range. Some cats stay quite dramatic in their drops to nadir though.