Type 1 is an autoimmune disorder.  The body destroys the beta cells of the pancreas and thus loses the ability to produce insulin.  There's only a genetic component to it in about 10-15% of cases.  The rest of the time it's just dumb luck that the body's immune system decides to attack itself.  It's never the person's fault when this happens and I always feel sorry for them.  This is what medicine should treat, not the fat fucks that can't stop stuffing their cake holes. I wish your shitlord friend the best.  I have a cousin with type 1 and she's exactly like him.  She works out and eats healthy but is still inconvenienced by the problem on a regular basis.