Important facts: 
Dogs:  Dogs with diabetes like humans with Type 1 diabetes have no ability to produce insulin on their own. Their pancreatic beta cells have been destroyed so without external sources of insulin, they will suffer and die. There are no exceptions to this. 

Cats: The situation with cats and people with Type 2 diabetes is different. Their beta cells have some degree of functionality such that it is possible to actually restore normal blood sugar in some cases. As you know, we have three diabetic cats. One, Amadeus has half-day honeymoons about once every 10 days. Another, Tiggy, has full day honeymoons about one every 21 days and for the past two months has had completely normal blood glucose levels. She isn't producing 100% of her own insulin so we continue to give her half a unit of PZI twice daily.

Unfortunately, Precious never honeymooned and was on NPH 4 times a day for a long time. Her situation was probably complicated by the massive cancer that eventually took her life.

Edward Murray.  Ed is married to a veterinarian and they own a diabetic dog as well as two diabetic cats.

Honeymoon:  The temporary remission of hyperglycemia that occurs in some people and felines, when some insulin secretion resumes for a short time, usually a few months or maybe only for a day, before stopping again. Cats tend to honeymoon.

The thing an owner must be aware of is that the honeymoon can end as quickly as it came. With daily testing an owner will know if their cat's glucose is elevated or normal and they must trust the results of the urine or blood test.

Giving insulin to a cat honeymooning can be fatal BUT withholding insulin from a cat that is no longer honeymooning can also have tragic results.

Please read   "The Tragedy of Tommy Boy"

Important Message from Edward Murray
The real lesson is not to ignore vets and go with your gut instinct, but to do BLOOD GLUCOSE testing.

Vets can't really tell what is going on doing with one BG at the clinic, or even a fructosamine (which I doubt was calibrated for cat blood).

But by the same token, the owner can't tell what is going on. High blood sugar and low blood sugar often have the same set of symptoms. You can only tell for sure by looking at the blood glucose, and not just once in a while. You need to monitor it twice daily and periodically do a curve so you get a complete picture of what is happening.

We do have some cats who I can imagine would be a bear to do blood testing on, but . . .

When we got Tiggy Tuga from the shelter where they were about to put her down for being diabetic, she bit and scratched and twisted and turned the first few times I tried testing her.

After a particularly nasty bite, I grabbed her by the scruff and sat her on the table in front of me at eye level and let her know what happened to diabetics in our house.

ONE--You WILL have your blood glucose tested twice daily and you will have a curve every few weeks or anytime something doesn't seem right! TWO--You can yell and scream all you want, but you WILL NOT bite or scratch me!

Do you understand?

Good!

I would have never believed that would work, but it did. Tiggy screams her head off when I pick her up to do her blood glucose, but she doesn't fight me.

She has been honeymooning for over two months. Every BG has been completely normal.
But she still gets tested twice a day! And she still screams her head off, although at this point, it is strictly pro forma screaming.