We actually don't recommend using any of the oral diabetes medications in cats. The way they work is to try to force the pancreas to make more insulin. Cat's have the unique ability for their pancreas to heal and resume working again, but to do that healing, it needs rest, not more work.
The oral meds can look like they're working for a short time, but in almost all cases, the cat will end up needing insulin anyway but by forcing the pancreas to do that extra work, the beta cells needed to produce insulin have been burned out so any chance of achieving remission is lost.
Is there a specific reason you're using the oral meds instead of insulin or was it just what your vet recommended?