While a diagnosis of feline diabetes may seem scary and overwhelming, of all the diseases your cat can have, this is one of the most managable ones.
Here are some suggestions for when you meet with your vet.
1) What insulin are they going to prescribe and what dose? Many cats have been successfully regulated and sometimes able to go into remission using Lantus, Levemir and PZI. ProZinc is another good insulin but a very new one. If your vet prescribes Lantus, ask for the script for the cartridges or Solostar pens. Even though the initial cost is more expensive than the vial, it is actually more economical. Most people only get 1-2 months use out of a vial before the insulin stops working. With the scripts for the pens or cartridges, you get 5 times the amount of use for about 1 1/2 the cost of the vials.
For the dose we recommend starting low and slow. If your vet tries to start at a dose more than 1 unit twice a day, tell them you are not comfortable with that. For cats, insulin is not dosed by the cat's weight. Also, you need to give your cat at least one week on a consistant dose before making any changes. It takes that long before the body can adjust to the dose and respond properly.
2) Ask your vet if they support hometesting. You do not need your vet's permission to hometest, but it is great if they support it. Also, you do not need any special "animal" glucose meter to test. Buy any glucose meter used for humans. An economical meter to use that gets high marks is Walmart's Relion brand meters. If you can, pick up the meter and strips before you go to the vet and they can show you how to test.
3) Do not let your vet try to talk you into prescription foods. Most of us feed our cats either Fancy Feast or Friskies. There is a link to Janet and Binky's food list on the page for links. Look for foods under 10 in the carbs column and as high a number as possible in the protein column. Also get rid of the dry food. You will be surprised how much difference just a diet change can make in the blood glucose levels.
There is a lot of information on this site, so enjoy reading it. But don't become too overwhelmed by it. Also, feel free to ask any questions at any time. There is almost always someone online and we will be glad to help you.