Brian, quick random story that your comment made me think of: Like three years before I was diagnosed, my cat was misdiagnosed with diabetes! It turned out that she had a horrible infection the vet didn't find, but that infection had raised her blood sugar. So I was giving that poor little kitty insulin for a day or two before I joined an online forum for owners of cats with diabetes, was told by those users to get a glucose meter, and discovered that her BG was FINE despite her getting worse. I took her back to the same pet clinic but to a different vet, who expressed skepticism at diabetes, ran tests, and discovered she was SEPTIC. :(
(Jeez. If I'd known then what I do today, I'd have known right away that she didn't have any symptoms of diabetes other than fatigue, illness can cause slightly elevated BGs, and more tests were in order before giving my cat medicine that could just as easily kill someone when not needed as save someone when it is.)