I really agree with sticking to the dose for at least 5 days in the beginning. It takes time for the cat to adjust to getting insulin. I didn't change dose for the first 2 weeks and Tinkles had some very high numbers, over 600. He did begin to respond after the first week, but it takes time, patience is very important.
In our experience, ProZinc is a quirky insulin, the more you jump around with the dose, the more confused and frustrated you will get. Small, infrequent dose changes work the best, especially in the beginning. It can take several days to see the effect of the dose change, so if you change every 2-3 days, you may not be giving the dose a chance to settle. I know others may suggest different timing on dose changes, but that has been our experience with ProZinc, specifically.
As far as injection location, I'm not sure if that is a poor absorption area, I know the scruff of the neck is a bad spot. I inject along the side of the back, between the front and back legs and about an inch down from the spine. Since Mickey is a heavy cat, you may be having issues with injecting into the fat layer, which delays absorption from what I remember reading. You could try changing where you inject and see if that helps with response, but I'm not sure where to tell you to try. Maybe someone else has a suggestion?
