Since many/most people gain weight
when they quit smoking
, your husband should start trying to lose, now, particularly if you think he might be diabetic or even pre-diabetic, which can be reversed.
He needs to eat plenty of lean protein, such as chicken, fish, other lean meats, low/no fat dairy, beans, etc. He should also center most of his meals around veggies, which are very low in calories (leave off the sauces and use oils and herbs for seasoning).