Ok I finally got a new battery for the ketone meter and testing him . 5.6! Now I would normally be scared out of my wits but he is perfectly fine. Eating fine, peeing, pooping, purring, playing. No issues whatsoever. I am of course keeping a very watchful eye on him but he must be the kind of cat that can have ketones yet not DKA.
@Sandy and Black Kitty your thoughts? He is definitely not lethargic, or lack of appetite. I am also doubting the meter - last time I checked and got a 4.5 on the reading - I immediately did another test with same drop of blood and it was 3.2. So I think I will keep watching for any signs but not rush to the emergency vet.