it's not just sugar. https://en.wikipedia.org/wiki/Glycemic_index#Grouping
all simple carbs are the devil, but we can't possibly feed billions of people actually healthy food - organic vegetables, nuts, and animal products, so come drink your corn syrup.
The sugar industry (topic of this article) can only be blamed for sugar, though -- not all high-GI foods.
And you can replace "sugar" in what I said earlier with "high-GI foods" and it doesn't change a thing. Persistent high blood sugar is diabetes; it isn't dietary.