If you have Utopia Silver then you have the good stuff. The Silver Puppy is an excellent machine. I know of none better, though I like the new Utopia Silver machine for the budget minded who do not want or need the extra clamshell casings and bells and whistles (such as a an automatic stirrer). The new Silver Edge looks like a really good one too.
I have one of the Silver Bullet machines now. Maybe the folks at Silver Edge and Silver Puppy will send me one of theirs so I can do a side by side comparison.
I would not give the kitty with diabetes nearly as much as the one with the cold. Though I doubt there would be a problem, way too much silver might put a strain on the kidneys.