If his blood sugar is always high, he might eat differently to still take advantage of that one
or two glasses of beer
or wine.
Or he might slow down on the alcohol. Everyone's body is different, but I've found, what works for me at least, is a balance. If I'm going out socially, and might be inclined to "have a few" I make sure I watch my numbers, watch the food I'm eating, and make sure I walk around a bit (my form of excercise).