Why do diabetic foot ulcers occur?

DFU causes
(Causes of Diabetic Foot)

Neuropathy

The etiology of Diabetic Foot Ulcers (DFU) is inseparable from the symptoms of diabetes, with neuropathy being one of the most common complications of diabetes. About half of the patients will develop this symptom during the progression of the disease, with distal neuropathy (peripheral neuropathy) being the most common1. This can cause damage to the nervous system of the limbs, including the sensory, motor, and autonomic nerves of the foot2,3：

• Sensory neuropathy：

  Protective sensation (such as tactile, pressure, and vibration perceptions and so on) becomes dull or lost, making it difficult to detect pain or discomfort caused by foot injuries. This also leads to neglect in foot care or underestimating the severity of foot injuries.

• Motor neuropathy：

  Atrophy of the small muscles of the foot affects the usual posture or movements when standing or walking, causing excessive or prolonged pressure on specific areas of the foot, which can lead to severe foot deformities.

• Autonomic neuropathy：

  The foot loses some of its physiological regulatory abilities. For example, a lack of sweat regulation can lead to dry, cracked skin, causing fissures that may lead to potentially infectious wounds, thereby reducing the foot's protection against external injuries.

Peripheral Vascular Disease

In addition, about half of the DFU patients will also have peripheral arterial disease. Poor blood circulation in the lower limbs leads to ischemic symptoms in the feet, such as skin necrosis, which can further exacerbate diabetic foot ulcers3.

Uneven Foot Stress

Neuropathic or vascular changes in the patient's foot, combined with external mechanical pressure (which could be prolonged repetitive stress or instantaneous injury), cause the skin's keratin to proliferate, forming calluses (hardened layers of skin that form as a result of scabbing). This induces an inflammatory response and bleeding. When these calluses peel off, the subcutaneous tissue is exposed3.

Want to know what complications diabetic ulcers can further cause?

"DFU Complications: The Consequences of Progressive Deterioration"

Reference：
• Feldman EL et al. Nat Rev Dis Primers. 2019;5(1):41.
• Armstrong DG et al. N Engl J Med. 2017;376(24):2367-2375.
• Armstrong DG et al. JAMA. 2023;330(1):62-75.