OmgFor me it was 'How insulin works, what it does and how to use it'. Obviously I knew insulin lowered glucose levels but that was about it. Sent off from the hospital with life saving and equally dangerous 'medicine' without a clue how it really worked or why they were giving me two lots (shown one practice run on how to inject on an orange!), practically told 'use it or die in a week'. I soon learned that it really isn't a question of inject x amount, eat x amount and it'll all be hunky dory.
That's akin to malpractice surely
Any type one, has my respect for all the juggling and higher maths required for this.
But to start off with such a stark "good luck, you'll need it" from those you turn to for life saving help...
Stay well @KK123