Sally:
The information and the links that Jill posted above are directly from the Queensland protocol. It is what everything we do here is based on. If you are measuring ins and outs (i.e., fluid in and fluid out), how are you measuring? I hope it's not by instinct. A research protocol, such as the version of the Queensland protocol that's been cited, is from a veterinary journal. There are precise methods of measuring fluid intake and output. I have a sneaky suspicion you are not measuring precisely. While PU/PD are symptoms of diabetes, they are not the most effective or precise ways of ascertaining blood glucose values. In fact, I doubt there's even a loose correlation. They are symptoms, not BG equivalents.
I'm honestly not sure what you want us to tell you. Personally, I think it would help if you took several giant steps backwards and made an attempt to hear what we're saying. The bottom line is that we want Mugsy to be safe. How you are approaching diabetes management is not safe. Let me put this in a different perspective, if this were a child, would you not test? Of course, the big difference is a child might tell you if he or she didn't feel good (i.e. was hypoglycemic). A cat can go to sleep and what's really happening is a hypoglycemia induced coma. At that point, if you don't know what you're seeing, the likely result is your cat is dying. No one wants that to happen. Mugsy's numbers dropped over 400 points today and for all we know are still dropping. If you are lucky enough to catch the drop and have fed HC, I expect that Mugsy will be in the 500s tonight or tomorrow. (Of course, you won't know where his numbers are because you aren't testing at night.) To not sugar coat this, your approach to treating Mugsy's diabetes is putting your cat's life at risk.
Please post on Health to see if there is someone who lives in your area who will help you learn to test. Ask if someone can provide you with urine glucose testing information in the interim. Urine glucose testing is not an effective means of garnering real time information but it's better than what your getting.