5-10% of people have diabetes. Globally, 6.3% of people have type 2 and in the US 11.6% of people have it (had no idea it was that many but I'm not surprised). Type 2 can be typically be managed by oral meds, diet, and exercise. In the US, 0.5% of people have type 1 and require insulin to live, globally that's about 0.1%.

I don't personally find most physical things that important, like a goddamn Pixar movie

Not totally sure where Pixar come into play here but a lot of people do find physical things important. People who have type 1 either care about it or they go blind, lose a foot, or die. They generally don't go around talking to people about their diabetes.

As far as kids go, at least when I was growing up, they are fucking brutal. In 1st and 2nd grade I had a lazy eye which was corrected by glasses and an eye patch (not the cool pirate kind, it was a skin-colored sticker) and I got teased quite a bit. Insulin pumps didn't exist back then, I would imagine little kids with insulin pumps today get teased at most schools. Pretty good chance a T1D Barbie will make a difference to a lot of those kids.