I've got a specific answer and a general one. The specific one: Shortly after I started insulin and neither I nor my doctor had a clue (he was treating me as Type 2), I basically had way too much insulin and had a low that caused me to lose consciousness. I came out of it, realized what happened and was able to treat myself, though barely. It was like moving through molasses to test and treat, but I did it. My liver apparently chimed in with some glucose to wake me up and I survived. But it scared me. So I worked on learning more and nothing like that has happened since (it was in 2009). But the good thing to come out of it was I knew that even with a bad miscalculation like that, I survived. I've since had lows (though not like that) and I've handled them. Not fun, but not the end of the world. Ditto highs. I correct and move on or come on here for help in figuring something out.
The more general answer: I'm frequently aware how lucky I am to not be diagnosed until age 58. First of all, obviously is not having to deal with D through all those years of a busy life. But it's more than that. By the time you get into your 50s, unless you have lived a very sheltered life, you have been through a lot. And you have not only survived, but, hopefully grown from the things you went through. So you gain a belief that you can deal with anything - not that it will be easy or without obstacles, but that you can and will do what you need to do to get through it.
Some people are just naturally pretty fearless and take life in their stride. I've never been one of those people, but for that very reason I know the dangers of letting myself give in to fears. If I thought of all the things that could happen, and do happen to people on a daily basis, I'd literally be paralyzed with fear. Not how I want to live. So I look at the possible dangers and do what I can to prevent them. Sometimes. I have also discovered that you can't prevent every "what if" because you'd a very dull life, or one where you spent all your time "preventing" instead of living.
There have been times in my life when I was too fragile to deal with all the dangers and fears. And there are still short periods where I get overwhelmed and need to reduce the stress. At such times I've been known to limit reading about certain things, set aside some issues for later, stop watching the news, tell people "I don't want to hear it". I've never had to (or wanted to) stop reading TuD posts, but there have been times I see threads I don't want or need to read.I have trains of thought I realize are unproductive, leading not to solutions but dwelling on problems, so I cut them off. I always limit drama and negativity around me and have had to cut some long time friends out of my life to do so. Bottom line? I do what I do for me to stay positive and move forward without a lot of time spent in fear or regret.