I've worked on diabetes medical devices for about 8 years, did some research on diabetes to augment my ability to work on said diabetes medical devices, and personally know several people with type 1 diabetes and as well type 2 diabetes.

Did you mean instead to write: Sugar causes type 2 diabetes, not fat?

I suppose high sugar consumption could cause it, but it doesn't look like that is the typical mechanism.

Shows us something peer reviewed.

Edit: I haven't found anything to definitively say Greger is a quack, but given that searching his name brings up mainly alternative medicine type sites, I remain suspicious.