Prozinc is a 12 hour insulin (it is called an "in and out" insulin vs. a longer lasting, depot insulin like Lantus) but when it does go longer, then there could be a need for a possible reduction. The only way you know that is if you know what the mid-cycle (nadir) number is. The other reason could be how the cat reacts to the insulin in the day versus the night time. Some cats will go higher in one 12 hour cycle compared to say a day time cycle. The reason why some cats run high at night is because the cat doesn't eat that much or there is less stress. With my cat, the insulin doesn't last the full 12 hours at night i.e. his AMPS is usually higher than his PMPS numbers. During the day, he does go the full 12 hours and a little more. I don't know why he does that.. So I have to shoot an almost 11/13 schedule. Prozinc you can choose to have more flexible schedule.
So. I am rambling, but to summarize, there could be a couple of reasons why Prozinc may go a little longer than 12 hours; needs a reduction in dose and sometimes it is just how the cat assimilates the insulin. Others may have other theories to add to. Good question, Matt.
Edited Update: I thought of a third reason why Prozinc may last more than 12 hours and that is when the pancreas does wake up or sputter for a time during a cycle. That could add to the 12 hour.
