Welcome Sue and Sam. Yes, it does appear to be ProZinc because Sue has mostly posted on the PZI ISG, and Sam started there on ProZinc.
It looks like you have been doing the sugar dance a couple of years, Sue. Digging thorough old posts, I see Sam was Dx 2/2009, put on Vetsulin. Sometime between then and January 2010, he went OTJ. Back on the juice in September 2010. He's a small boy, isn't he Sue, and 15, maybe 16 now?
Sue, has Samwise had a dental since he went back on insulin? Any senior bloodwork in the past year? Are you working with a vet you trust and like? What is Sam eating?