Whole potatoes have some vitamins and fiber. Brown sugar has some, processed sugar has none. Peeled potatoes have little more nutrition than white sugar, and the same or worse effect on insulin response, which is the key of type 2 diabetes. Mainly what I was pointing out is that something like mashed potatoes is the same as sugar, maybe worse, and that "type 2 diabetes happens from too much sugar" might as well be "type 2 diabetes happens from too much french fries" but the real issue is total carbohydrate intake. In practice, Type 2 issues combine with lifestyle, as in if you're a marathon runner or body builder, eat as many carbs as you want. If not, watch all carbs.