What happened to my cat?

I have a four year old fit and healthy tom.

A couple of months ago he collapsed during the night and I took him to the emergency vet.

They said his blood sugar level was very low (consistent with him being injected with too much insulin - but he's not diabetic!) and he was hypothermic and dehydrated.

He recovered slowly; at one point we thought he was blind and would have brain damage. He is almost fully recovered but still 'bungles it' sometimes when he tries to jump because he's not as skilled as he was at that sort of thing.

My question is: what happened to him? He didn't have any signs of injury and he didn't vomit or have diarrhea.

Could it possibly be concussion from a fall I didn't know about?

Any responses would be very welcome.

I'm so sorry to hear about your baby. Unfortunately I don't have anything to offer as far as help goes but you and he will be in my thoughts and prayers.

I hope he is getting better now. That sounds like what happened to my Raven last year but we don't have an emergency vet so I had to just keep him comfortable. Everything I researched pointed to poison so that's what I figured. Especially since the neighbor in front of me had the pest control people out spraying around their house and yard a few days before he got sick.

I wish him the best for a full recovery.

Thank you for your kind words . The first thing I thought was poison but no vomiting.