I read the intro to diabetes and it said that even though you're cat is drinking a lot, losing weight and his blood sugar tests high, only a vet can confirm diabetes. What else would those symptoms indicate? It's not my first time at the diabetic rodeo. I had a cat a few years back that I was giving shots to twice a day and who did very well for 5 yrs, not only didn't continue to loose weight, he gained back the weight he lost, which my vet said he has never seen. He died of surgery complications unrelated to diabetes. So, when I noticed that one of my older cats (12 yrs old) was drinking a lot and lost weight, I tested her and her sugar was over 300. I'm ready to start her on insulin, but now that I read the intro (because I couldn't remember what dose I was giving my other cat), I'm wondering just what else it could possibly be and exactly what the vet would do to "diagnose" diabetes. My guess is, test her blood sugar, possible do a fructose test or maybe a curve and then charge me 100's of dollars.