Type I is of course different than type II. Addressing type II, the disease is from
the overcompensation of refined carbohydrate, along with under consumption of micro nutrients. Consistent with the above answers, is a collagen deficit which is due to a vitamin C deficit. Vitamin C is needed to cross link fibers at the frequently repeated proline and lysine positions after hydrogenation by vitamin C.
The causes are certainly many. The reduced oxygen supply is important but not the only one. It is necessary to speak of reduced blood supply and of altered regulation, in situ, of the blood supply. In the patient with type II diabetes rheological changes, microangiopathy and macroangiopathy are a deadly mix for the well-being of the tissues.
Very few obese adult onset diabetics pay attention to injecting vitamins and trace minerals. For example, that thin skin is likely due to a collagen deficit which is a vitamin C deficit. Also, a chromium deficit is associated with glucose intolerance. Then there is the overcompensation of refined carbohydrate itself.
Weight loss using a high protein low to very low refined carbohydrate diet along with an amply supply of micro nutrient and trace mineral with a Mediterranean diet will work.