I've been very open about it since I was diagnoesd 13 years ago. In fact, when we moved 10 years ago, I had to make sure my neighbors knew about it, just in case they saw me passed out on the front lawn. It was especially necessary since I had a toddler at home and my husband travelled frequently at that time.
There are so many assumptions about diabetes. I've been told many times I ate too much sugar when I was younger and my pancreas gave up. Um, if that were the base, we'd have millions more type 1s. Then go explain this to small children. You're right about type 2s, the assumption of being fat and lazy. I have a friend who is ridiculously skinny and she has type 2.
I'd tell someone. Just in case you get into some kind of trouble and 911 is needed, then they can inform the EMTs of your diabetes. I don't find it anything to be embarassed about. Fortunately we don't get some raised D on our forehead to alert people to our medical condition.
I'm curious, what is holding you back from letting your friends know of your diabetes?