I have never used ginger for my kitties. Although it has been shown in some cases to help with lowering glucose levels in people, that does not necessarily mean it would do the same in a kitty.
This article says ginger is safe for a kitty:
http://familypet.com/is-it-safe-to-give-my-cat-ginger-and-in-what-form/
However the article does state:
"As always, the caveat is to thoroughly discuss giving ginger to your cat with your veterinarian. Ginger needs to be administered according to weight and also keep in mind that just because something is natural doesn’t mean there’s no potential for a harmful interaction. Discontinue use at the first sign of allergy."
If you know a holistic vet you might want to discuss whether using ginger would be of benefit and how much to use.