I agree with Tara that the diabetes needs to be your first and primary concern right now. And Red & Rover has given you some leads to finding a more appropriate diet to help manage both conditions. You want to find a low carb food that is also low in Phosphorus. As mentioned dry food is generally too high in carbs for our diabetics however if you are located in the US, there are a couple of options one of which suggests it is good for kitties with kidney issues (Young Again) although I cannot vouch for that claim. Perhaps something to ask on the CRF site.
I'm not sure if I am interpreting your spreadsheet information correctly but if I am, the dose of insulin may need adjusting. A normal curve for each cycle would be a starting point at a higher reading, BG drops lower and then goes start back up again till the end of the cycle. Some of your readings are low at the beginning of the cycle and then go up. This could indicate the dose of insulin is too high. I would suggest you get some more mid cycle tests between +4 and +7 hours post shot to see how low the dose is taking your boy.
It would be very helpful if you could set up one of our spreadsheets and link it here so we can see the data you have so far in a format we are familiar with and won't misinterpret. The instructions for setting up the spreadsheet are
HERE and
THIS document explains how to use the spreadsheet. We don't deal in clock times here because our members reside all over the globe so we capture our BG tests as pre-shot tests and by the number of hours since the shot was administered.
It would also be helpful if you could set up a Signature (the light grey text below our messages). To do this hover over your screen name in upper right screen. This drops down a menu and you select Signature from the left column. A text box will appear into which you can type information like your name, your cat's name, medical history (ie CKD, any history of ketones/DKA etc.), the food kitty is currently eating, the type of glucometer (human or pet) you are using, the type of insulin and your general location so that any recommendations for food etc. are pertinent to you. When you get the spreadsheet set, you can put the link in your signature so the sheet is available to anyone here offering assistance. If you need any help with any of this, just holler.
As for changing insulin, it's still early days. ProZinc is a good insulin for cats as Tara can attest, and the best insulin is the one that works for your cat. I think you need to give the ProZinc a bit more of a chance before making a switch. It's quite possible with a little dose tweaking and a change of diet, you will start to see some improvement.
my kitty is stage 2 ckd and diabetic but in remission. She was just diagnosed a few weeks ago. I was directed to 
