I am confused too, Denise. You have tried the lower doses and the higher doses and sometimes you need some decent numbers for a test or two, but nothing seems to hold. If you hadn't tried another insulin already, I would suggest that.
You are sure he is not getting into the dry food, right? I wonder if the pain of his neuropathy messes up his numbers, or whether it is something other than neuropathy. Have you had a full check up at the vet?
I know it is discouraging - for us too. We want to help and want to have ideas of what you can do.
I will vote with Robin and hope we see some results.