sorry to hear his honeymoon is over! but kudos to you for catching him quickly!
you want to feed as much as it takes to hold his weight steady. If his numbers are high and he's not metabolizing the nutrition from his food he may need more food for a while.
i agree with sienne about not holding doses too long. it will still take a few days for his depot to equalize in his body with the dose, but typically for cats to go into remission again, you need to both deal with whatever brought him out of remission and be more aggressive with dosing. Teeth are a common reason for a cat to come out of remission, so even if the vet saw nothing you may want to have a dental done. They can't get a really good look until the cat is under anesthesia. A UTI is another possibility. Are you adding water to MeowMeow's food? I'd add as much as he'll tolerate and still eat it.
Has he still been eating low carb canned food?
If your goal is a second remission, Tight Regulation is your best chance. You want to get his body back into normal numbers (under 120) as quickly as is safely possible, and try to hold him there. Some cats will go back into remission again, so I wouldn't give up hope on it at all.
You might want to reread the Tight Regulation sticky to remember how the protocol works. Just a reminder that Lantus dosing is based upon the nadir that a dose will get him to - so you want to have a mid-cycle check on each cycle to know what he's doing. The protocol suggests testing at +3, 6, 9 and preshots for the first several days when beginning on Lantus. You don't want him to surprise you by reacting well and going low.
Welcome back!
