(Diabetes isn't caused by sugar intake.)

Not directly, no. But indirectly, by increasing weight gain and eventual metabolic syndrome, if eaten in excess… which was my point :)

Type 1 isn't caused by any of this stuff. Type 2 is caused by excess body fat -- consuming too many calories in total over a long period of time. It doesn't matter what the composition of those calories is. You can eat mostly sugar, at maintenance levels, and never be at risk for T2D.