Diabetic Foot Ulcer - How does this happen? Patients with Diabetes Mellitus are at higher risk for a lot of bad things, but two in particular are at play here. The first is atherosclerosis, which (simply put) is when cholesterol accumulates in the walls of arteries, slowly restricting blood flow. The second is neuropathy. When the human body can’t process glucose it can be converted to another form of sugar called sorbitol. When this happens in a cell, like a nerve cell, it causes water to rush in and the cell will swell up and POP. Also, since the arteries are atherosclerotic the nerves aren’t getting continuous blood supply, also killing them. Combine these two events and then add a minor incident, like the patient getting a small cut on their foot. Now they can’t feel it and therefore know to treat the wound (prevent infection), and the wound can’t get adequate blood flow to promote healing. So the wound just festers and gets worse, turning into a giant necrotic ulcer.