Welcome Tina!
I'm very glad that you switched the diet! The grain-free varieties of Wellness canned are great to feed a diabetic. If you go
here and put your zip code in, it will tell you what stores in your area carry Wellness. Usually independently owned pet food stores sell it for far cheaper than the chain stores like Petsmart, and you can get it in 12 oz cans which makes it less expensive. You can also feed many other brands of food, including some less expensive grocery store options. Here's a link to the cat food nutrition charts:
http://www.felinediabetes.com/diabetic-cat-diets.htm. You just want to stick to canned food that is under 10% carbohydrates.
We do not recommend feeding ANY dry food to a diabetic cat. Even the lower carb dry foods can still keep blood sugar high. Also, diabetes is not the only disease caused by dry food. Cat's evolved in the desert, so they don't have thirst drives like dogs or humans. They never make up for the loss of moisture in their food at the water bowl, no matter how much they drink, so they end up chronically dehydrated. This causes all sorts of health problems, including kidney disease, urinary tract disease, and others. Here's a web site written by a vet that explains the basics of feline nutrition and the health problems related to dry food:
www.catinfo.org. I would get rid of all the dry food right away and feed canned food only. The
American Animal Hospital Association Diabetes Guidelines for cats also recommends a canned only diet.
A cat cannot be regulated at the vet. Vet stress inflates blood glucose values and makes them unreliable, and regulation usually takes several weeks or months. Diabetes in cats is best treated at home, just like with humans. There is also absolutely no reason to hospitalize your cat, and if that is what your vet is telling you, you should find a new vet that is more current with feline diabetes. If you post your city and state, perhaps a member here can suggest a vet that is current in feline diabetes.
We all test our cats' blood glucose at home, using an human meter. The Relion meters at Walmart are good quality and inexpensive, so they are pretty popular here. Testing sounds like it's hard at first, but after you and your cat get used to it, it's really, really easy! Most cats are fine with it within a week or two. We get a tiny blood drop from the tips of their ears, which have very few nerve endings, so it's not painful at all for the cat. What some cats don't like at first is you doing something new and strange and possibly restraining them, as well sensing their human's nervousness. After a week or so of low carb treats after every test, they not only tolerate it, some will actually like it and start purring for you! Here's a great video that shows you how:
http://www.youtube.com/watch?v=_zE12-4fVn8
I would urge you to start testing at home immediately to see if she needs insulin. Most cats do need a small amount of insulin for a period of time before they go into remission. Most diabetic cats will also go into remission if you get them on the right insulin (Lantus or Levemir), feed them a low carb, canned only diet, and adjust their insulin dose based off of daily numbers obtained via home testing. The longer you leave the diabetes untreated, the less likely it is you will be able to get your cat into remission, and the more likely it is she'll need insulin permanently. Also, untreated diabetes can cause complications like deadly diabetic ketoacidosis, organ damage, and diabetic neuropathy.