Even though diabetes is absolutely terrible, I know that this is an aspect of my life I have control over. So many other things could be going wrong outside of my control, but I can predict my diabetes fairly closely. When my parents are fighting, I have no control over it. There is no "If I do ______, then they will ______" On the other hand, if my bloodsugar is 250, I know I can change it for the better.
I know this seems like a stupid reason, but I feel that I can't let something bad happen to me if I see it coming. I'm too competitive to let it slip past my defenses.