| Personally I think this is a bit more than just diabetes-related. Everyone has a different approach to parenting and what they feel is 'good' parenting. Generally what people consider 'good' parenting tends to be how they were raised. You said yourself that your parents gave you relative freedom. I bet your boyfriend's parents had a firm bedtime for him. I know I did, and I didn't even have diabetes at the time.
Depending on how long your boyfriend has been around, it may be that he wants to play an active role in bringing up your son. Which means it is probably driving him crazy when he sees you make parenting decisions that don't tally with his idea of 'good' parenting. The diabetes issue is probably just a way of him trying to find reasons to convince you of his way, rather than yours.
I'm no parenting and relationship expert, but I think the two of you need to sit down and decide how much of a role he is going to play in your son's upbringing. Which means you may have to compromise on some areas if you want him involved. I'd suggest that it's not worth fighting over what time your son goes to bed.  | 
