Diabetic Foot Assessment Before a Wound Develops
Diabetic foot care should not begin only when an ulcer appears. It should start before any wound develops, by identifying people who are at increased risk and may need closer follow-up and targeted preventive care.
A person with diabetes may have reduced sensation, impaired blood flow, changes in foot shape, or early pressure-related skin damage without being aware of them. The absence of pain or other symptoms does not necessarily mean that the feet are healthy. Regular examination is therefore essential, even when the skin appears intact and there is no open wound.
Who is at risk of developing a diabetic foot ulcer?
According to the International Working Group on the Diabetic Foot (IWGDF), a person with diabetes is considered at risk when at least one of the following is present:
- Loss of protective sensation (LOPS) due to diabetic peripheral neuropathy.
- Peripheral artery disease (PAD), which reduces blood flow to the feet.
The risk increases further when one or more additional factors are present:
- Foot deformities, such as claw toes, hammer toes, prominent bones, or limited joint movement.
- Callus, cracks, blisters, or bleeding beneath a callus.
- A previous diabetic foot ulcer.
- A previous minor or major lower-extremity amputation.
- End-stage renal disease.
- Inappropriate, tight, hard, worn, or poorly fitting footwear.
- Limited mobility or difficulty inspecting and caring for the feet.
- Impaired vision, obesity, cognitive difficulties, social isolation, poor access to healthcare, or financial constraints.
A previously ulcerated foot should not be considered completely “normal” after healing. It is considered to be in remission and requires lifelong prevention and regular specialist follow-up to reduce ulcer recurrence.
Specialist Diabetic Foot Assessment
A comprehensive assessment involves much more than a quick look at the foot. The specialist begins with a detailed medical history, including:
- Duration and control of diabetes.
- Numbness, tingling, burning, or pain in the feet.
- Pain at rest or while walking.
- Previous wounds, infections, surgery, or amputation.
- Kidney disease, cardiovascular disease, smoking, and other vascular risk factors.
- Daily foot-care habits, mobility, footwear, and ability to inspect the soles.
Both feet should be examined while the patient is lying down and standing. Weight-bearing can reveal deformities and pressure points that may not be visible at rest.
The clinical examination usually includes:
- Inspection of the skin for dryness, colour or temperature changes, callus, cracks, blisters, fungal infection, swelling, and early pressure-related damage.
- Examination for deformities, bony prominences, joint stiffness, and areas of increased pressure.
- Assessment of walking pattern, balance, mobility, and the ability to perform daily foot care.
- Inspection of shoes and socks for poor fit, wear, seams, or foreign objects that could cause repeated trauma.
Callus, redness, or bleeding beneath a callus over a pressure point should never be ignored. These findings may indicate excessive mechanical loading before an ulcer develops and the need for professional callus treatment, footwear modification, specialist insoles, or orthotic support.
Tests for loss of protective sensation
Loss of protective sensation is one of the most important risk factors for diabetic foot ulceration. A person may step on a sharp object, develop pressure from a tight shoe, or burn the foot without feeling pain or recognising that damage has occurred.
The main tests are simple, painless, and usually performed in the clinic.
10 g monofilament test
A 10 g monofilament is a thin nylon fibre that bends when a standard amount of pressure is applied. The examiner touches specific areas of the sole and toes while the patient keeps their eyes closed.
If the pressure is not felt at one or more tested sites, protective sensation may be reduced or absent. The test helps identify risk in a foot that may not reliably detect trauma or excessive pressure.
The monofilament result is best interpreted together with another sensory test and the overall clinical examination as part of prevention.
128 Hz tuning fork test
A vibrating 128 Hz tuning fork is usually placed over a bony area of the big toe. The patient is asked whether vibration is felt and when it stops.
Reduced or absent vibration sensation supports the diagnosis of peripheral neuropathy, identifies greater ulcer risk, and indicates an increased need for preventive care.
Ipswich Touch Test
The Ipswich Touch Test assesses light-touch sensation by briefly touching selected toes. It can be used as a simple alternative when a monofilament or tuning fork is not immediately available.
It is a useful ulcer-risk screening test, but it does not replace a complete specialist assessment when neuropathy is suspected.
A diagnosis of neuropathy does not mean that an ulcer will definitely develop. It does mean, however, that the foot has lost an important warning system: pain. Daily protection, suitable footwear, and regular review therefore become much more important.
Assessment of blood flow and peripheral artery disease
Adequate blood flow is essential for healthy skin, ulcer prevention, and the healing of even small injuries. Peripheral artery disease may be silent, especially in people who also have neuropathy and do not feel the typical leg pain while walking.
Initial assessment may include:
- Questions about pain when walking, rest pain, previous vascular procedures, smoking, and cardiovascular disease.
- Inspection of skin colour, temperature, hair loss, and tissue condition.
- Palpation of pulses on the top and inside of the foot.
Arterial Doppler assessment
A handheld Doppler device evaluates the presence and quality of blood-flow signals in the arteries of the foot.
The waveform pattern provides useful information about circulation. An abnormal or monophasic waveform may indicate peripheral artery disease, increase ulcer risk, and signal the need for further vascular assessment.
Ankle-brachial index (ABI)
The ABI compares blood pressure at the ankle with blood pressure in the arm. It is commonly used to assess arterial circulation in the legs.
In diabetes, calcification may make leg arteries difficult to compress and produce a falsely high ABI. For this reason, the result should not be interpreted in isolation when assessing ulcer risk.
Toe pressure and toe-brachial index (TBI)
Toe pressure measures blood pressure in the toes, while the TBI compares toe pressure with arm pressure.
These tests can be particularly useful in vascular risk assessment because the toe arteries are often less affected by calcification than arteries at the ankle.
No single bedside test can completely exclude peripheral artery disease or fully define ulcer risk. The specialist combines symptoms, pulse examination, Doppler waveforms, ABI, and TBI findings and may request vascular imaging or referral when results are abnormal or uncertainty remains.
IWGDF risk classification
For the complete evidence-based recommendations, visit the official IWGDF guidelines website.
The IWGDF risk classification combines loss of protective sensation, peripheral artery disease, foot deformity, previous ulcer or amputation, and end-stage renal disease.
The category helps determine how often the feet should be assessed and how intensive preventive care should be.
| Category | Ulcer risk | Main characteristics | Recommended screening frequency |
|---|---|---|---|
| 0 | Very low | No LOPS and no PAD | Once a year |
| 1 | Low | LOPS or PAD | Every 6–12 months |
| 2 | Moderate | LOPS with PAD, LOPS with foot deformity, or PAD with foot deformity | Every 3–6 months |
| 3 | High | LOPS or PAD combined with a previous ulcer, lower-extremity amputation, or end-stage renal disease | Every 1–3 months |
These screening intervals are minimum recommendations. More frequent review may be needed according to the patient’s clinical condition, self-care capacity, and access to appropriate footwear and preventive treatment.
Prevention begins before the wound
Once risk has been identified, preventing an ulcer should become part of everyday life. Important measures include:
- Inspecting both feet every day, including the soles and the spaces between the toes.
- Washing the feet daily and drying them carefully, especially between the toes.
- Using moisturiser on dry skin, but not between the toes.
- Wearing well-fitting shoes and suitable socks.
- Avoiding walking barefoot, in socks alone, or in thin-soled slippers.
- Checking the inside of each shoe before putting it on.
- Seeking professional treatment for callus, fungal infection, and ingrown or thickened nails.
- Using prescribed insoles, orthoses, or specialist footwear when indicated.
- Attending regular foot examinations at the interval recommended for the individual risk category.
Redness, warmth, swelling, a blister, a crack, bleeding beneath a callus, skin discolouration, or any new break in the skin should prompt early contact with a healthcare professional. When sensation is reduced, an ulcer may develop without pain, so waiting for pain can delay treatment.
When a Diabetic Foot Ulcer Has Already Developed
The assessment described above is intended primarily for people with diabetes who are at risk but do not currently have an active ulcer. Once a wound develops, the priorities change. Assessment must move beyond identifying future risk and determine the severity of the existing ulcer, the factors preventing healing, and whether infection, ischaemia, deep-tissue involvement, or osteomyelitis is threatening the limb.
A diabetic foot ulcer may appear small on the surface while extending deeply into the underlying tissues. It should therefore be assessed promptly and systematically by a trained multidisciplinary diabetic foot team.
Clinical examination of the ulcer
The first step is a detailed examination of the ulcer, the entire foot, and the leg. The clinician should document:
- Location: forefoot, midfoot, heel, toe, interdigital space, dorsum, side, or sole of the foot.
- Size: length, width, and surface area, usually recorded in centimetres.
- Depth: whether the ulcer is limited to the skin and subcutaneous tissue, reaches tendon or muscle, or extends to bone.
- Wound bed: granulation tissue, slough, necrotic tissue, callus, drainage, odour, or exposed structures.
- Surrounding skin: redness, warmth, swelling, maceration, callus, cracks, colour change, or signs of pressure.
- Possible cause: abnormal loading, deformity, repetitive trauma, poorly fitting footwear, walking barefoot, or an injury that was not felt because of neuropathy.
The examination should also assess foot deformity, joint stiffness, high-pressure areas, oedema, mobility, walking pattern, footwear, nutritional status, kidney disease, glucose control, and any social or practical difficulty that may affect self-care or adherence to treatment.[1]
Is the ulcer infected?
Diabetic foot infection is primarily a clinical diagnosis. A positive wound culture alone does not prove infection, because chronic wounds may contain colonising bacteria without tissue invasion.[1,2]
According to the IWGDF/IDSA criteria, infection is diagnosed when at least two of the following are present and there is no more likely non-infectious explanation:
- Local swelling or induration
- Redness around the wound
- Local tenderness or pain
- Increased local warmth
- Purulent discharge
Other findings – including increasing exudate, malodour, skin discolouration, necrosis, gangrene, blisters, crepitus, rapidly spreading inflammation, or unexpected wound deterioration – may raise concern for a more extensive or severe infection and require urgent specialist assessment.
In people with diabetes, neuropathy, peripheral artery disease, or impaired immune response may make infection less obvious. Fever, marked pain, or a high white-cell count may be absent even when a clinically important infection is present.[1,2]
The IWGDF/IDSA system classifies infection as follows:
| Infection grade | Clinical meaning |
|---|---|
| Uninfected | No local or systemic signs of infection |
| Mild | Local infection involving only the skin and subcutaneous tissue, without systemic manifestations |
| Moderate | Infection that is more extensive or involves deeper tissues, without systemic manifestations |
| Severe | Infection associated with systemic manifestations of infection |
Moderate or severe infection, extensive gangrene, suspected deep abscess, compartment involvement, necrotising infection, or severe ischaemia requires urgent assessment by surgical and vascular specialists.[1-3]
Clinically uninfected diabetic foot ulcers should not be treated with systemic or local antibiotics when the aim is to prevent infection or promote ulcer healing.[2]
Wound culture and blood tests
When there is clinical suspicion of infection, a microbiological sample may be required to identify the causative organisms and guide antibiotic treatment. The preferred approach is to collect a deep tissue specimen aseptically after cleansing and debridement, usually by curettage or biopsy.[1,2]
A superficial swab is easier to obtain but may identify surface-colonising organisms rather than those responsible for the deeper infection. Conventional culture and antibiotic-susceptibility testing remain the recommended first-line microbiological methods.[2]
Blood tests may support the assessment when the clinical examination is equivocal or the infection appears more severe. Tests may include:
- Full blood count
- C-reactive protein (CRP)
- Erythrocyte sedimentation rate (ESR)
- Procalcitonin (PCT), in selected cases
- Blood glucose, renal function, electrolytes, and other relevant metabolic tests
These blood tests cannot diagnose soft-tissue infection or osteomyelitis on their own. Raised inflammatory markers, interpreted together with the clinical findings and imaging, may increase suspicion of a deeper infection.[2]
Tests for osteomyelitis
Osteomyelitis is an infection of the underlying bone. It should be considered when an ulcer is deep, chronic, recurrent, located over a bony prominence, associated with visible bone, or accompanied by a swollen “sausage” toe.[2]
Initial assessment usually combines:
- Probe-to-bone test: a sterile blunt metal probe is gently introduced into the ulcer to determine whether bone can be felt. A positive result increases the likelihood of osteomyelitis, particularly in a high-risk ulcer, but does not confirm the diagnosis on its own.
- Plain X-rays: used to identify bone erosion, cortical disruption, periosteal reaction, gas in the deeper tissues, a foreign body, or deformity.
- Inflammatory markers: ESR, CRP, and sometimes PCT, interpreted alongside the clinical and radiological findings.
No single test can reliably confirm or exclude osteomyelitis in every patient. The probe-to-bone test, plain radiographs, and inflammatory markers should therefore be interpreted together.[2]
When diagnostic uncertainty remains after the clinical examination, blood tests, and plain X-rays, magnetic resonance imaging (MRI) is the preferred advanced imaging examination. MRI can provide detailed information about bone-marrow involvement, soft-tissue infection, abscesses, and the anatomical extent of disease, particularly when surgery is being considered.[2]
If MRI is contraindicated or unavailable, PET, leukocyte scintigraphy, or SPECT may be considered. When microbiological confirmation is required, a bone specimen for culture may be obtained intraoperatively or percutaneously through intact skin.[2]
Assessment of circulation and healing potential
Every diabetic foot ulcer requires assessment for peripheral artery disease (PAD). Palpation of the foot pulses is important, but normal or apparently present pulses alone cannot reliably exclude impaired blood flow in a person with diabetes.[1,3]
Clinical assessment includes skin temperature and colour, capillary refill, hair loss, tissue loss, gangrene, and palpation of the pedal pulses. Objective testing may include:
- Pedal Doppler waveforms
- Ankle-brachial index (ABI)
- Toe pressure and toe-brachial index (TBI)
- Transcutaneous oxygen pressure (TcPO2) or skin perfusion pressure (SPP) when toe pressure cannot be measured or further prognostic information is needed
Peripheral artery disease is less likely when pedal Doppler waveforms are triphasic or biphasic, the ABI is 0.9-1.3, and the TBI is at least 0.70. However, no single test can completely exclude PAD in diabetes.[1,3]
Severe ischaemia requires urgent vascular assessment. Important warning findings include:
- ABI below 0.4
- Ankle pressure below 50 mmHg
- Toe pressure below 30 mmHg
- TcPO2 below 30 mmHg
- Monophasic or absent pedal Doppler waveforms
In a patient with PAD and a foot ulcer, infection or gangrene further increases the urgency of consultation with a vascular specialist regarding possible revascularisation.[3]
Standardised classification
A standardised assessment helps the multidisciplinary team communicate clearly, describe disease severity, and select the appropriate pathway of care:
- SINBAD records Site, Ischaemia, Neuropathy, Bacterial infection, Area, and Depth. It provides a concise description of the ulcer and supports communication and triage.
- IWGDF/IDSA classification grades the presence and severity of diabetic foot infection.
- WIfI assesses Wound, Ischaemia, and foot Infection. In people with diabetes, PAD, and a foot ulcer or gangrene, it helps estimate the likelihood of healing and the risk of major amputation.[1-3]
These systems support clinical judgement but do not replace an individual assessment of the patient, the limb, and the ulcer.
Key message
A diabetic foot ulcer is not simply a wound on the skin. It may reflect neuropathy, impaired circulation, infection, abnormal mechanical pressure, or bone involvement. Early clinical examination, wound measurement, infection assessment, deep-tissue culture when indicated, appropriate imaging for suspected osteomyelitis, and objective vascular testing allow the multidisciplinary team to develop an individual treatment plan and reduce the risk of limb loss.
