I wouldn't. ProZinc is flexible and once you have data, you will have options. But it is too early. he has only been on insulin 2 days, right?
Sometimes it takes a while for them to settle into a dose - that may be it. You started at 2 units. It could be that the dose is too high. (check out Sev's spreadsheet) Data will make these answers clearer.
It is scary to see high numbers. If you are testing for ketones and testing blood sugars, you are keeping him safe until you have enough numbers to see patterns and trends.
One thing you can do to help you and us and your vet is to start a spreadsheet. Then when you come on the board and ask for advice, we have his history right there. If you want help getting it done, send me a pm.