Wow Angela that is just horrible. That would be unfair dismissal for being fired for low blood sugar. And the other boss should be pulled up for discrimination.
I refuse to go to the bathroom to do mine. I have always done mine in public, where and whenever. It's a part of who I am and I refuse to hide it like it's something to be ashamed of. If I am out with someone that hasn't seen me do it before I just let them know, hey I am a diabetic so will be doing a needle. Usually they have no problem, unless it's a person with a needle phobia. If I know that about them I give them a heads up and they look away for the 2 seconds it takes me to do it. Most times people don't even know I have done it and it's usually at the lunch or dinner table, it's pretty quick so unless I draw attention to it, they probably won't notice. Plus as I use pens and not syringes it is a lot less intimidating for potential onlookers.