amputations

Don't know all the causes, but I think that the main one is this:
Uncontrolled blood sugars lead to Neuropathy (damage to your nerves, that mean you have a reduced capacity to feel things with your extremities - numb toes is the classic example).
Because your feeling is reduced, you don't notice if small cuts or sores appear on the affected area (usually your feet), which heal slowly (another consequence of uncontrolled blood sugars) and can easily become infected.
Gangarine can develop in the infected part of your body, possibly leading eventually to amputation.

A linked cause is peripheral vascular/ arterial disease, basically narrowing of the arteries leading to a lack of oxygenated blood to the extremities. Risk factors for PAD are uncontrolled D,obesity, high blood pressure, high cholesterol, smoking and lack of exercise.
http://en.wikipedia.org/wiki/Peripheral ... ar_disease