Not that it's a competition, but T1D can and does just come out of left field and fuck you over. Not only for annoyingly prosaic things like forgetting a Snickers in the car and passing out alone and never waking up, but also sudden cardiac death is an order of magnitude higher.

I had cancer, it was shit, and yes, there's always a chance its not done with me, but at least the cause of death won't be "finally forgot a snack".