As Diane said, people on the Lantus forum tend to post often, but you don't have to. You can just link to your previous post when you do, so it's easy to see where you were the last time you posted. Posting often makes it easier for people to help you, we get used to seeing your cat's name and numbers and start seeing patterns.
She does not have any symptoms and it's great. I was like you at first, very defensive and thinking my vet made a mistake, Bella did not have symptoms, she could not be sick. Then I started looking at her more closely. She was drinking. A lot. And she never used to drink. She was peeing a lot, a lot more than her drinking would explain, and so much that she would miss her box. And she lost weight. I was trying to have her lose weight for years but then she started losing, and drinking, and peeing, and it all made sense: those are diabetes' symptoms. That, and of course the blood glucose numbers. It is not normal for a cat to have blood glucose in the 300s. That is diabetes.
You don't want her to stay in those high numbers too long, or she could get toxicity due to the high blood glucose. Her kidneys will suffer, her nerves too. Some cats develop neuropathy months after diagnosis, mine did. She was not even able to stand on the back legs with her front paws on a box. She could not jump anymore, she was limping, and that was after her numbers started improving. Diabetes takes time befre you can see symptoms, but you don't want that to happen.
I am sorry you got off with a bad impression here. People here are giving their time to help others, sometimes there might be something going on, with their own cat maybe, or something else, and an answer might seem agressive, but it's not personal. It might also be that somebody really wants to help you but cannot, because they are missing some information. Try not to take it personnally, keep asking questions, I honestly think this is the best place to get a cat on the way to being regulated.
For my cat, the fact that I joined here is really what made a difference. If you look at her SS, her numbers started improving when I started to follow what
@Bandit's Mom and
@tiffmaxee and others were telling me to do. Some days I was frustrated, I thought it did not make sense, my vet did not agree, I wanted to go faster, but the important thig is that the method works.
Sorry for the long post