Factors that influence the development of foot ulcers involve damage to the nerves, blood vessels and structure of the foot. They include:

• Diabetic neuropathy. Nerve damage resulting from high glucose (blood sugar). Types of neuropathy that contribute to foot ulcers include:
  
  
• • Peripheral neuropathy. Damage to the peripheral nerves, including those serving the legs. The nerve damage eventually impairs sensation, which can make a person unaware of puncture injuries (e.g., stepping on a nail), pressure injuries (e.g., abrasion caused by tight shoes) or thermal injuries (e.g., scalding bath water).
    
    
  • Autonomic neuropathy. Damage to the autonomic nerves that control involuntary functions, such as heart rate and blood pressure. This condition can cause decreased sweating, which can dry and crack the skin, resulting in ulcer formation or infection.
    
    
  • Focal neuropathy. Nerve damage that develops quickly and affects one body part, such as the legs.
    
    
  • Proximal neuropathy. Nerve damage that affects the hips, thighs and buttocks.

• Peripheral arterial disease (PAD). Restriction or blockage of the peripheral arteries (those outside of the heart and brain), including the tibial and peroneal arteries that serve the lower leg. PAD is a type of atherosclerosis, which is a hardening and narrowing of the arteries due to buildup of plaque. PAD is four times more common among people with diabetes. It is exacerbated by high blood pressure, smoking and hyperlipidemia (too much fat in the bloodstream). The main symptom of PAD is claudication (pain in the legs when walking).
  
  
• Structural abnormalities. Problems with the structure of the foot, which can cause high-pressure areas of skin more prone to ulcer development. They include:
  
  
• • Callus. Area of hardened skin.
    
    
  • Corn. Horny thickening of the skin due to friction or pressure.
    
    
  • Bunion. Painful swelling of the bursa (a sac that contains friction-reducing fluid) at the big toe’s first joint, with that toe displaced toward the other toes.
    
    
  • Hammertoe. A claw-like bending of the toe joints.
    
    
  • Charcot foot. A joint damaged and deformed by repeated injuries due to impaired sensation. This condition is often caused by diabetic neuropathy.
    
    
• Incorrect footwear. Research has demonstrated that many people who developed diabetic foot ulcers were not wearing their appropriate shoe size.

In addition, rates of diabetic ulcers are higher among smokers than nonsmokers, among men than women, among longtime patients than people who have recently developed diabetes, among the obese than the thin, and among whites and Hispanics than people of other races.

A pressure ulcer can occur when the tissues of the body are damaged from continued contact with a contributing factor. Conditions that may cause pressure ulcers include:

• Immobility, whether from weakness, paralysis or positioning devices sometimes used in nursing homes or hospitals.
  
  
• Inappropriate mattress, cushion or bedding for a patient.
  
  
• Neuropathy. People with nerve damage cannot sense discomfort or pain causing the tissue breakdown.
  
  
• Exposure to moisture such as urine or sweat.
  
  
• Malnourishment. Lack of protein, vitamins and other nutrients impairs skin integrity and slows healing.
  
  
• Poorly fitting clothes or footwear.