I am sorry if this comes across as harsh.
But I've been where you are, adopting a cat and later learning that they have diabetes. Scared about the commitment, scared about the costs, wondering if it is all worth it... my first post ever on FDMB was expressing my concerns over that.
I was seriously considering surrendering Scooter to the SPCA because I couldn't afford/wasn't sure if I was going to be able to commit to treatment. It is expensive. It is overwhelming. It takes commitment. But consider this - had you known Zoey was sick, would you have adopted her? No. And neither would anyone else. If you surrender her back to a place like the HS or SPCA, she will probably be euthanized without further consideration simply because, who wants to adopt a sick cat, when they could adopt a fun, playful, healthy kitten instead? Even if that kitten could just as likely get diabetes, CRF, CHF, asthma, etc?
I just could not give Scooter up to a shelter that would put him down simply because he required a bit more care than once or twice a day feeding and a litter box clean here and there. He is young, loving, and his quality of life, even with the diabetes, was too good to even CONSIDER euthanasia. He was skinny, constantly exhausted, flooding the litter box, always hungry, and his fur was clumpy... but he still had so much life in him. Yes, I could've adopted him out to someone else. But you are going to have a hard time finding a home for a cat that has a chronic disease. Again, not many people voluntarily take in sick cats. Even if you surrender her back to this pure bred shelter, they are going to have a heck of a time finding her a new home that will treat her. And even if someone were to take her, how can you make sure they are willing to commit to a safe, studied, treatment protocol, and she is not going to wind up on a deadly dose of Humulin or left untreated with DKA? I trusted myself more than anyone else with Scooter's care. I took that upon myself when I adopted him. Disease or not, that is what you commit to when you adopt a pet. You came to FDMB instead of just giving up - that shows me you have a will to make this work out.
There IS help out there for low income folks taking care of diabetic cats. If you are willing to commit to a proper treatment regime, DCIN WILL help you with funds. Scooter is a DCIN sponsored kitty. They have covered most of his vet bills, taxi costs to and from the emergency vet, his insulin cost, lancets, and even syringes when I was really strapped for cash. Without DCIN, I would not have been able to keep Scooter in my situation back then. Please, do contact them, if it would enable you to keep Zoey. I am about to start a new job soon and now I will be able to care for most of Scooter's needs. I just needed that extra help in the beginning. It all worked out in the end.
I have not regretted committing to treat Scooter for one second. This disease has brought us closer together and we share a bond deeper than any other pet I've had before. With feeding low carb, administering proper insulin, and home testing, I am in control of his diabetes. He is well regulated, has gained 3 pounds, his fur has smoothed, his litter box activities have returned to normal, and he runs around playing like a kitten again. And even though he's just a cat, I truly think he knows what I've done for him has made him feel better. He has become such an amazing companion to me.
I do not know why you seem hesitant to the idea of wet food. I know transitioning a dry addict to canned is tough. But trust me, it makes a world of difference, and as others said, you might even find Zoey is regulated on food alone. Even though CORE dry is "low carb", it can still keep the numbers high. Some cats are just more sensitive to starches. Please, read the replies in your thread "Hard Decisions" as you were given a lot of good advice that could really help yours and Zoey's situation. Give us a reply when you have read it. We are trying to help... but we cannot help if you are not willing to listen...