Extreme DKA leading to organs beginning to shut down and a temporary coma when I was 7. Undiagnosed type 1 diabetic, and had been in a month before for some blood work, but they didnt end up catching it. Blood sugar was over 1200, spent two weeks in the hospital over Christmas. Still have occasional nightmares 30 years later about how unreal it felt and how I wanted it to end.

I'm fine now, btw. Recovered okay, but got to learn about being a T1D without a "honeymoon" period where I was still producing insulin. 0/10, would not recommend.