didn't you say he had lost weight as well Mel?

Mild alarm bells are ringing for me.......smell his breath, is the a fruity but acidy smell kinda like nail polish remover but sweet? That would be a big clue. If his weight loss and drinking were due to diabetes you would expect normally this breath thing because the body is making toxic acids called ketones.....

He could just be at that age though where they drink like a fish but it wouldn't hurt to get him a finger ***** test just to be sure......

sorry if that alarms you.....just sharing my knowledge base for what it worth....