Is it ok for my diabetic father to drink?

My 70 year old father has diabetes. He takes his insulin as normal. However I worry is that he drinks a beer at 4:00 pm, than has about three Jack & water drinks in the evening while watching TV. He also snacks on chips and salsa. He either falls asleep on his chair or goes into a light coma than (I am guessing) but he is very difficult to wake up. I can yell, shake him or softly call him, but it does not wake him up right away. At 10:00 pm I try to wake him up to go into his bedroom to sleep. Is this normal?

I know he is depressed, at times he does not want to have visitors. He will not go for walks. It is irritating to me.