Diabetic foot ulcer

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.

Foot ulcer at a pressure site 

 

 

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 1 

UT Grade 2 

UT Grade 3 

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?

• An ulcer associated with other causes of peripheral neuropathy, such as leprosy
• Other causes of arterial ulcer
• Venous 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%.