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Diabetic foot ulcer

Authors: Vanessa Ngan, Staff Writer, 2003. Revised: Dr Sashika Samaranayaka, Post Graduate Year 1, Department of Dermatology, Middlemore Hospital Auckland, New Zealand; Hon Assoc Prof Paul Jarrett, Dermatologist, Clinical Head Dermatology, Middlemore Hospital and Department of Medicine, The University of Auckland, Auckland, New Zealand. Copy edited by Gus Mitchell. January 2021.


What is a diabetic foot ulcer?

Diabetic foot ulcer is a skin sore with full thickness skin loss on the foot due to neuropathic and/or vascular complications in patients with type 1 or type 2 diabetes mellitus.

Who gets diabetic foot ulcer?

Diabetic foot ulcer has an annual incidence of 2–6% and affects up to 34% of diabetic patients during their lifetime. Risk factors for developing a diabetic foot ulcer include:

  • Type 2 diabetes being more common than type 1
  • A duration of diabetes of at least 10 years
  • Poor diabetic control and high haemoglobin A1c
  • Being male
  • A past history of diabetic foot ulcer.

What causes diabetic foot ulcer?

Diabetic foot ulcers are caused by neuropathic and/or vascular complications of diabetes mellitus.

Neuropathic ulcer

High blood sugar levels can damage the sensory nerves resulting in a peripheral neuropathy, with altered or complete loss of sensation and an inability to feel pain. Peripheral neuropathy develops in approximately 50% of adults with diabetes, increasing the risk of injury to the feet from pressure, cuts, or bruises.

Vascular ulcer

Blood vessels can also be damaged by long-standing high blood sugar levels, decreasing blood flow to the feet (ischaemia) and/or skin (microangiopathy). This can result in poor wound healing.

What are the clinical features of diabetic foot ulcer?

A diabetic foot ulcer is a skin sore with full thickness skin loss often preceded by a haemorrhagic subepidermal blister. The ulcer typically develops within a callosity on a pressure site, with a circular punched out appearance. It is often painless, leading to a delay in presentation to a health professional. Tissue around the ulcer may become black, and gangrene may develop. Pedal pulses may be absent and reduced sensation can be demonstrated.

Diabetic foot ulcer

The severity of a diabetic foot ulcer can be graded and staged. There are many different classification systems. The University of Texas (UT) classification is a widely used, validated system (Table 1).

Table 1. University of Texas (UT) classification of diabetic foot ulcer

UT Grade UT Stage
0: Pre- or post-ulcerative or healed wound A: No infection or ischaemia
1: Superficial wound not involving tendon, capsule, or bone B: Infection present
2: Wound penetrating to tendon or capsule C: Ischaemia present
3: Wound penetrating to bone or joint D: Infection and ischaemia present

Grading foot ulcer

What are the complications of diabetic foot ulcer?

Diabetic foot ulcer is particularly prone to secondary infection resulting in:

  • Wound infection
  • Cellulitis
  • Osteomyelitis.

How is diabetic foot ulcer diagnosed?

Diabetic foot ulcer is a clinical diagnosis of a painless foot ulcer in a patient with a long history of poorly controlled diabetes mellitus.

Investigations may include:

  • Swabs for secondary infection
  • X-rays for bone involvement
  • Angiography.

What is the differential diagnosis for diabetic foot ulcer?

What is the treatment for diabetic foot ulcer?

Prevention of diabetic foot ulcer

  • Optimise diabetes control to reduce neuropathic and vascular complications
  • Smoking cessation
  • Regular examination of the at-risk foot, and careful toenail trimming
  • Prompt treatment of non-ulcerative conditions such as tinea pedis or cracked heels
  • Appropriate footwear — properly fitting soft shoes or made-to-measure insoles
  • Exercise and physiotherapy
  • Education of patient, family, and healthcare providers

General measures

  • Multidisciplinary care — may include endocrinologist, podiatrist, diabetes education nurse, wound care nurse, neurologist, vascular surgeon, and/or orthopaedic surgeon
  • Pressure reduction — appropriate footwear, crutches
  • Control of blood sugar levels
  • Prevention of secondary infection

Specific measures

  • Treatment of secondary infection
  • Ulcer debridement
  • Dressings
  • Adjuvant therapies — negative pressure wound therapy, ulcer excision and grafting, topical or hyperbaric oxygen, human growth factors, and/or amputation

What is the outcome for diabetic foot ulcer?

Diabetic foot ulcer may:

  • Heal over weeks to months
  • Re-ulcerate — recurrence rate is 40% within one year, 60% by three years, and 65% at five years
  • Result in lower extremity amputation in 14–24%.

The five-year mortality rate has been estimated to be 42%.



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