Diabetic Foot: Types, Causes, Symptoms, Complications, Treatment & Prevention

Diabetic Foot Definition

The term “diabetic foot” encompasses a range of conditions, which are foot complications resulting from prolonged high blood sugar levels damaging nerves and blood vessels in the feet resulting from a combination of peripheral neuropathy (nerve damage), poor blood circulation (peripheral arterial disease), and infection. If not properly managed, these factors make the foot more vulnerable to ulcers, sores, deformities, and even amputations. The condition is common among patients with long-standing or poorly controlled diabetes.

Diabetic foot problems may not seem severe, but they are the most common and serious complication of diabetes, as they often take a long time to heal. Unfortunately, more patients with diabetes are hospitalized due to foot wounds or infections than due to nephropathy (any disease or damage to the kidney), retinopathy (any damage to the retina of the eyes), heart attack, and stroke. 

Early detection and management by an endocrinologist or diabetologist can significantly reduce the risk of severe complications.

Diabetic Foot Meaning

Diabetic foot is a complex joint and bone disorder affecting the ankle and foot in patients with persistent diabetes, primarily caused by peripheral neuropathy.

Prevalence of Diabetic Foot

Diabetic Foot (DF) is among the most serious complications of diabetes mellitus that results in hospital admissions and burdens the healthcare system. Foot disease affects nearly 6% of individuals with diabetes and includes infections, ulcerations, or tissue destruction in the foot.

Prevalence of Diabetic Foot Worldwide

• The global prevalence of diabetic foot ulcers is estimated at 6.3% among individuals with diabetes.
• Around 15%–25% of people with diabetes are at risk of developing a foot ulcer during their lifetime.
• Diabetic foot complications are responsible for more hospitalizations than any other complication of diabetes.
• The estimated prevalence of diabetic foot infections (DFIs) ranges from 6% to 11%. Neuropathy is recognized as the most significant factor contributing to infections in diabetic foot wounds.

Prevalence of Diabetic Foot in India

• India holds a significant position in the global landscape of diabetes prevalence as it has become the diabetes capital of the world, with a projected 10.9 crore patients with diabetes by 2035. India ranks second (after China) with more than 6.68 crore diabetics in the age group of 20-70 years. 
• The prevalence of diabetes in India is 8.6%, and as of 2013, more than 10 lakh Indians die each year due to diabetes-related causes.
• Approximately 15% of diabetics in India are affected by foot ulcers, and 1 lakh amputations are performed annually due to diabetes-related foot infections.
• Diabetic foot ulcers are linked to high levels of morbidity, mortality, and significant financial costs.

Types of Diabetic Foot Problems

Diabetic foot conditions are broadly classified based on the underlying cause such as neuropathy, ischemia, or infection, each affecting the foot's structure and healing ability in different ways. The diabetic foot classification is as follows:

Diabetic Neuropathy (Neuropathic Foot: diabetic foot neuropathy)

• Loss of sensation in the feet
• Symptoms include tingling, numbness & burning pain

Ischemic Foot

• Symptoms include cold feet, shiny skin, and absent pulses
• Caused by peripheral arterial disease (PAD)

Neuroischemic Foot

• Open wounds or sores that occur on the feet of people with diabetes
• Caused by a combination of peripheral neuropathy (nerve damage) and ischemia (reduced blood flow)

Charcot Foot

• A serious complication resulting in bone and joint damage
• Causes foot deformities such as a “rocker bottom” appearance

Infected Diabetic Foot

• Bacterial infections in ulcers or deep tissues.
• May progress to cellulitis, abscesses, or osteomyelitis (bone infection).

Diabetic Foot Causes

Diabetic foot problems are primarily caused by high blood sugar damaging nerves which damages blood vessels, leading to nerve damage (neuropathy) and poor circulation, making the feet more vulnerable to injury, poor healing, and infection. The following are the diabetic foot causes:

• Peripheral Neuropathy: This is nerve damage caused by high blood sugar, leading to loss of feeling in the feet. Without pain sensation, small cuts or pressure points go unnoticed and can turn into serious wounds.

• Peripheral Arterial Disease (PAD): PAD reduces blood flow to the legs and feet, making it hard for wounds to heal. Poor circulation increases the risk of infections and ulcers.

• Uncontrolled diabetes: It leads to neuropathy and peripheral arterial disease through complex metabolic pathways.

• High Blood Sugar Levels: Consistently high blood sugar weakens the immune system, damages nerves and blood vessels, and slows down healing—setting the stage for diabetic foot complications.

• Occlusive Footwear (shoes or boots that enclose the feet tightly): Wearing improper footwear that encloses the feet tightly, limiting airflow and potentially trapping moisture, can lead to excessive sweating and increase the risk of fungal infections. It also increases the risk of pressure ulcers and trauma.

• Poor Foot Hygiene: Allows microbial entry and infection.

• Trauma or Minor Injuries: Can escalate quickly due to reduced sensation.

• Smoking: Narrows blood vessels, reducing blood supply.

Diabetic Foot Symptoms

Diabetic foot signs and symptoms usually develop gradually over months or years due to prolonged high blood sugar levels. Early signs often go unnoticed until complications begin to surface.

• Pain (diabetic foot pain): Tingling, burning, or pain in the feet

• Numbness: Loss of feeling in the feet or toes

• Swelling: Swelling in the feet or ankles

• Skin changes: Dry, cracked skin, changes in skin colour, or loss of hair on the feet

• Nail changes: Thickened, yellow toenails, or ingrown toenails

• Foot sores: Blisters, ulcers, infected corns, or sores that don't heal

• Foul smell: Foul-smelling discharge from a wound

• Foot deformities: Bunions, hammertoes, or Charcot's foot

• Foot odor: Foul odor from the feet

• Leg pain: Pain or cramping in the buttocks, thighs, or calves during physical activity

• Diabetic foot gangrene: Blackened toes or gangrene (late-stage)
  

Risk Factors of Diabetic Foot

Individuals are at a higher risk of developing diabetic foot complications if they have the following risk factors:

• Age: Older individuals are at a higher risk. 

• Sex: Males are more prone to develop diabetic foot disease. 

• Family history: A family history of diabetes can increase the risk.

• Poor blood sugar control: Uncontrolled blood sugar levels can damage nerves and blood vessels, increasing the risk of foot problems. 

• Kidney disease (Diabetic nephropathy): Kidney disease can be associated with an increased risk of diabetic foot disease. 

• Infections: Diabetic patients have a higher susceptibility to infections, which can worsen foot ulcers. 

Other risk factors:

• History of previous foot ulcers or amputations
• Visual impairment
• Foot deformities
• Limited mobility
• Inappropriate footwear

Diabetic Foot Complications

Ischaemia, neuropathy, and infection are the three pathological components that lead to diabetic foot complications, and they frequently occur together as an aetiologic triad. If untreated, diabetic foot can result in severe complications:

• Infections (Diabetic foot infection): Including cellulitis, abscess, and osteomyelitis

• Gangrene: Tissue death due to infection or lack of blood supply

• Foot Deformities: From Charcot's foot or improper healing

• Amputations: Partial or full removal of the foot or leg

• Sepsis: A life-threatening systemic infection

Diabetic Foot Diagnosis

Diagnosis involves clinical examination and specialized tests to assess the extent of nerve damage, blood flow, and infection, including:

Clinical Evaluation

• Inspection of skin, nails, ulcers
• Neurological examination (monofilament test, tuning fork)
• Palpation of foot pulses
• Gait and footwear assessment

Laboratory Tests

• HbA1c (glycaemic control)
• Complete blood count (to detect infection)
• ESR/CRP (to detect inflammation)
• Wound swab culture

Imaging

• X-ray (to detect bone deformities or osteomyelitis)
• Doppler ultrasound (to assess blood flow)
• MRI (for deeper infections)
• CT scan (for deeper infections)

Diabetic Foot Treatment

Diabetic foot management involves controlling the underlying diabetes, healing existing wounds, and protecting the foot from further injury. Early and proper care can significantly enhance outcomes and improve the quality of life for patients, including:

Wound Care (diabetic foot care)

• Regular cleaning and dressing of ulcers
• Debridement to remove dead tissue
• Negative pressure wound therapy (VAC)

Medications

• Antibiotics (oral or IV for infected ulcers)
• Pain management (neuropathic pain)
• Blood sugar control (insulin or oral antidiabetics)

Offloading

• Use of special shoes, insoles, or total contact casts to relieve pressure from ulcers

Surgical Intervention

• Drainage of abscesses
• Removal of necrotic tissue
• Revascularization procedures (angioplasty or bypass for PAD)
• Amputation in severe or gangrenous cases
  

Prevention of Diabetic Foot

Proactive foot care is essential to prevent diabetic foot complications:

• Daily foot inspection: Look for cuts, blisters, redness, or swelling.

• Proper footwear: Use well-fitted shoes; avoid walking barefoot.

• Good hygiene: Wash feet daily and keep them dry.

• Blood sugar control: Maintain target HbA1c levels.

• Routine podiatry check-ups: Especially if previous ulcers or neuropathy are present.

• Smoking cessation: Improves circulation.

• Nail care: Cut nails straight across; avoid injury.

• Education: Patients should be educated about foot care and risk signs.