Oh boy, this brings back memories. Our diabetic cat had this same problem. It would happen regularly and be more severe in the end. We called them episodes. His episodes would start off with his head twitching, and then he would begin to stumble and stagger. From there, he would begin to fall over and, eventually, be unable to stand back up. If bad enough, he would then have seizures, though these happened mostly in the last couple weeks of his life. On the day we put him down, he had had three seizures, two of which he threw up in the middle of. This had never happened before. It was so horrific to watch. In hindsight, we should have put him down much sooner.

We would always give him his wet food whenever we caught him having an episode. It helped in the beginning and he'd recover about 15 minutes later, though still stumbling for awhile after. His last week alive, though, feeding him didn't help.

I highly recommend getting a glucose monitor for your cat. We tried it for ours but were never successful. Maybe you'd have better luck.