Good morning and welcome Gary and pet parent. There is a great deal of information here on FDMB as well as a very supportive community.
I suggest you begin by reading the information on the Home page, "Getting Started" and "Education". It's a start on understanding feline diabetes and your role in treatment. Home testing is advocated here on the board, it's the best way to track your cat's blood sugar level on an immediate basis and allows you to see how a diet change or insulin therapy is affecting your cat, plus a critical tool for keeping your cat safe. If you are not home testing yet and want more information, we can help with that.
There is also a ton of information in the forums here on the board, about changing the diet for a sugar cat, about the different kinds of insulin, and how to integrate treating your cat's diabetes into your daily life.
Take a few deep breaths, know that you are going to find the help you need, do some reading. Post in the Main Health forum, let us know if Gary is currently on insulin, what kind, what is the dosage? What does Gary eat, how often? How did the vet determine that Gary is diabetic? Does he have any other health problems, conditions, issues? Again, post on the Main forum so that more members can see and respond, this Intro forum is the welcome mat, and we don't usually advise here. Link to the Main Health forum---->
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