@Uny_ - I read your post when you wrote it, then haven't got back to it for a number of reasons, so
@tim2000s 's nudge has worked pretty well.
When I read your post, your boss reminded me of someone I knew in corporate-land who was a complete nightmare; especially as she was in a position of some quite significant power and influence.
In summary, my interpretation is that your feel unsupported in your office environment, in terms of hypo safety net activity, and secondly, your boss appears to be pretty self-centric when going about her business.
I do agree with others that she may actually be pretty scared about the potential for having to inject you, in a crisis, and may even subconsciously, be removing herself from being around you to minimise the potential she would have to actually carry out that task. Just a contra view.
The reality is not everyone is a caring soul, and she probably hasn't been employed to look after you on trips. I know that sounds harsh, but I'm trying to put forward contra views to try to help you think of how she may be viewing things and to consider if some things could be approached a but differently.
In your office environment, is there not someone else who can be skilled in your deep hypo emergency treatment? Do you have an office First Aider? Do you share an office, or work in an open plan office? If so, should your first port of call not be those who work physically closest to you? If this person is clearly resisting the prospect with all her might, you should take control and take the potential away from her, by up-skilling other people. In any case, it is not an proper safety net if your safety is contingent on her being there. I'm assuming she has holidays, goes to meetings, even has sick leave, so who would help you then?
When the two of you are travelling, you may just have to do the best you can. If she's 100 yards ahead of you and you need to stop, unless you can summon the energy to shout very loud, she is useless to you anyway!?
How many hypos like this are you having? Is there anything you could do to perhaps lassen the chances of the airport type situation arising, by maybe ensuring you run a trifle higher when you're going through this process?
I appreciate not all hypos are avoidable, but if you're having lots of them, that that should surely be the primary focus of your efforts. Try to prevent the root cause. Clearly, that's very easy for me to say.
Initially, I suggest you think about the potential for taking her out of your immediate safety net loop, before you go to HR, because they will want to know what you have done about matters before talking to them. It could be that HR will then make a referral to Occupational Health (assuming you have such a department) to check you out and see what may need to be done.
Giving your manager feedback is always a tricky one, unless your company offers a 360 Feedback process as part of it's regular appraisal process (which I am assuming you have). It's not easy to give negative feedback without causing further discord, so in doing so, you really have to concentrate on facts, and documents situations she is likely to remember. It is also important that when you paint the picture of her shortcomings that you then don't just leave it as "what are you going to do about it?". That could been considered confrontational. You must follow up by saying something along the lines of, "When x, y or z situation arises, it makes me feel............"
Those feelings could be unsupported, unimportant, irrelevant, ignored, abandoned or whatever your descriptor words would be. Your boss can state categorically that she didn't do, or didn't mean to do these things, but she cannot tell you you did not feel as you did.
If that all seems a bit traumatic, then you could try to involve a union or another person to mediate in a meeting, but again that's tricky when you are, after all, going to have to continue to work with this person. She may be required to change her behaviour, but you cannot change her character.
If you elect to look for another job, again, it will be wise to try to really work on those hypos, because, in my experience you may not find takers queueing up to be your hypo safety net anywhere else either. In their shoes, at that time, they are dealing with someone who is very ill indeed. They have to assess the best course of action, then give you an injection you are incapable of giving yourself. I am clinically trained. I can give IV. I can insert lines in large vessels, when necessary, but I wouldn't be wringing my hands in glee at the prospect of being your hypo-buddie.
I'm sorry that's so very long, but I wanted to express some of the thoughts that have been going around in my head since reading your original post.
Really good luck with it all, because it looks to me like you have lots of thinking and planning on your hands.