7.1 Epidemiology and risk factors

Based on United Kingdom population surveys, diabetic foot problems are a common complication of diabetes with prevalences of 23-42% for neuropathy, 9-23% for vascular disease and 5-7% for foot ulceration. Amputation rates are higher in patients with diabetes than non-diabetic patients.³⁰²

Patients with diabetes are at increased risk of peripheral vascular disease (PVD), especially when other associated risk factors are present, e.g. smoking, hypertension and hypercholesterolaemia. Diabetic foot ulceration is principally associated with PVD and peripheral neuropathy, often in combination. Other factors associated with increased risk include previous amputation³⁰³, previous ulceration³⁰⁴, the presence of callus³⁰⁵, joint deformity³⁰⁶, visual/mobility problems³⁰⁷ and male sex³⁰⁴. The cumulative effect of these risk factors is at least additive.³⁰⁶

7.2 Care management

Much of the evidence supporting recommendations in this section describes specific interventions carried out with adults in a multidisciplinary context (comprising e.g. diabetes physician and specialist nurse, podiatrist, orthotist, vascular and orthopaedic surgeons) which have not been assessed in isolation. The recommendations therefore apply to comprehensive care delivered in a multidisciplinary setting to people post-puberty with diabetes.

7.2.1 PATIENT EDUCATION

Several studies of education in patients with little or no existing foot disease were identified however most of these involved very small patient numbers, used different endpoints and reported inconclusive findings. Only two large studies were identified which used significant lesions as endpoints. One indicated that, at 1 year follow up, where patients had agreed 'personalised behavioural contracts', there was a significant reduction in serious lesions.³⁰⁸ The second study showed no significant change in lesions and little or no effect of a general education program after 18 months follow up.³⁰⁹ Evidence level 1+

A single RCT suggested that intensive education may be effective in the prevention of amputation or recurrent ulceration in patients who have had previous diabetic foot disease.³¹⁰ This trial involved an unusual intervention which included frank presentation of the complications of diabetic foot disease to patients in the experimental group. This 'scare-tactic' may not be generalisable to all patient groups or settings, however the reduction in amputation and ulceration after one year was promsising and should be replicated in further trials in order to validate the technique. Evidence level 1+

Programmes which include education with podiatry show a positive effect on minor foot problems at relatively short follow up.^{311, 312} Evidence level 1+, 2++

Foot care education is recommended as part of a multidisciplinary approach in all patients with diabetes.

7.2.2 STRUCTURED FOOT REVIEW

The absence of reliable symptoms and the high prevalence of asymptomatic disease make foot screening essential.³⁰² Evidence level 4

All patients with diabetes should be screened for foot disease.

There is no evidence to support the frequency of screening; however the guideline group considers that at least annual screening from the diagnosis of diabetes is appropriate.

Figure 1

Example protocol for the assessment of risk of the diabetic foot adapted from the tayside foot risk assessment protocol

Neuropathy screening can be performed either by using clinical neuropathy disability scores, 10 g monofilaments, or by use of vibration perception thresholds. All these methods, singly or in combination, have shown benefits in selecting patients at increased risk of foot ulceration.^{306, 313, 314} Evidence level 2+

Clinical neuropathy disability scores, 10 g monofilaments, or vibration perception thresholds are all appropriate methods for neuropathy screening.

Methods of screening for vascular insufficiency are less well defined. Absent pedal pulses are a guide to the presence of peripheral vascular disease and can be used for first line screening.^{315, 316} Evidence level 2+

Ankle pressure and pressure indices can be falsely elevated in patients with diabetes and should be interpreted with caution.³¹⁷

7.2.3 STRUCTURED FOOT CARE

Access to a podiatrist reduces the number and size of foot calluses and improves self-care.³¹¹ Evidence level 1+

In the absence of a multidisciplinary foot care team, foot lesions are more likely to lead to amputation. Multidisciplinary foot care teams allow intensive treatment and rapid access to orthopaedic and vascular surgery. This allows control of infection and revascularisation when needed. Wound healing and foot-saving amputations can then be successfully achieved, reducing the rate of major amputations.^{318, 319, 320} Adherence to locally established protocols may reduce length of stay and major complication rates.^{321, 322} Evidence level 2+

All patients with diabetes should have access to structured diabetic foot care.

7.2.4 FOOTWEAR, ORTHOSES AND TOTAL CONTACT CASTING

Plantar pressure using ordinary shoes is similar to barefoot. High-quality, cushioned-soled trainers can reduce plantar pressure more than ordinary shoes but not as much as custom-built shoes.^{323, 324} Evidence level 2++, 3

There is limited evidence that padded hosiery can reduce peak plantar pressures.³²⁵

Patients with diabetic foot disease should be advised to wear high-quality, cushioned-soled trainers rather than ordinary shoes.

The use of custom made foot orthoses and therapeutic footwear reduces the plantar callus thickness and incidence of ulcer relapse.^{312, 326, 327, 328} Patients who routinely wear their therapeutic shoes and orthoses are less likely to have ulcer relapse.³²⁹ Evidence level 1+, 2+, 3

Custom-built footwear or orthotic insoles should be used to reduce callus severity and ulcer recurrence.

A single RCT showed that treatment of patients with unilateral plantar ulcers using total contact casting can reduce the healing time to a mean of approximately 6 weeks.^{330, 331, 332} Evidence level 1+, 2+

Use of 'half shoes' reduces the time to complete closure of the ulcer to a mean of 10 weeks. ³³³ Evidence level 3

Patients who have unilateral plantar ulcers should be considered for treatment using total contact casting to optimise the healing rate of ulcers.

7.2.5 ARTERIAL RECONSTRUCTION

Patients with diabetes are more prone to peripheral vascular disease (PVD) than patients without diabetes. This includes both proximal (aorto-iliac and femoral) and distal (calf and foot) disease. Rates of limb salvage following distal bypass surgery are relatively high. Salvage rates of around 80% are reported in the initial presence of tissue loss (gangrene and ulceration).³³⁴ Increased frequency of distal bypass is associated with reduced frequency of amputation.^{335, 336, 337} Evidence level 2++

All patients with tissue loss and arterial disease should be considered for arterial reconstruction.

Forefoot and midfoot pressure reducing surgery can be safe and effective in selected groups of patients with diabetes who have non-ischaemic recurrent or refractory neuropathic ulceration at high pressure sites.^{338, 339} There is some evidence that pressure-reducing surgery can also be used prophylactically.^{340, 341} This is not standard practice in the UK and, in all cases, such surgery should only be undertaken by surgeons with specialist training. Evidence level 2+, 3

No evidence was found to support recommendations on the optimum stage to make a vascular intervention, whether amputation is the best intervention in terms of quality of life or the effectiveness of rehabilitation strategies.

7.3 Treatment

7.3.1 PHARMACOLOGICAL THERAPY

One RCT indicated that subcutaneous granulocyte-colony stimulating factor (g-csf) speeds up time for resolution of cellulitis in diabetic foot infections.³⁴² Growth factors such as topical RGD (arginine glycine aspartic acid) peptide matrix and CT-102 may increase the rate of closure of diabetic foot ulcers.^{343, 344} Topical becaplermin increases the rate of closure of diabetic foot ulcers.³⁴⁵ Evidence level 1+

In non-healing chronic neuropathic ulcers after optimal pressure relief, use of topical RGD peptide, CT-102 or becaplermin should be considered to speed up healing rates.

Subcutaneous g-csf should be considered in the treatment of diabetic foot infections.

No single broad spectrum antibiotic regimen was shown to be more effective over another in the treatment of diabetic foot ulcers.^{346, 347, 348, 349} Evidence level 1+

There is no evidence for the optimal duration or route of antibiotic treatment in treatment of diabetic foot ulcers.

Treatment of an infected diabetic foot ulcer should be commenced with a broad spectrum antibiotic regimen in conjunction with appropriate debridement. Subsequent antibiotic regimens may be modified with reference to bacteriology and clinical response.

7.3.2 TISSUE REPLACEMENT THERAPY AND MAGGOTS

Use of living human tissue replacement therapy shows a consistent increased rate of healing and increased number of completely healed ulcers in patients with diabetes^{350, 351, 352} Evidence level 1+

Treatment of diabetic ulcers using living human tissue replacement should be considered in refractory ulcers provided the patient meets strict exclusion criteria on infection, circulation and ulcer size and depth.

The evidence for maggot therapy is inconclusive, but clinical experience suggests that it is a useful alternative method of debridement.

7.3.3 PAINFUL DIABETIC NEUROPATHY

There is good evidence that the tricyclic antidepressants (TCAs) amitriptyline, imipramine and desipramine, the anticonvulsant carbamazepine and topical capsaicin are more effective than placebo in reducing symptoms of painful diabetic peripheral neuropathy.^{353, 354} Evidence level 1++

Gabapentin is superior to placebo in painful diabetic neuropathy and one RCT indicated it to have fewer side-effects than TCAs.³⁵⁵ Evidence level 1+

TCAs should be used as first line therapy in painful diabetic neuropathy.

Gabapentin is also recommended in painful diabetic neuropathy and is associated with fewer side effects than TCAs and older anticonvulsants.

Topical capsaicin should be considered for the relief of localised neuropathic pain.

7.3.4 CHARCOT'S FOOT

Charcot's foot is a neuroarthropathic process with osteoporosis, fracture, acute inflammation and disorganisation of foot architecture. During the acute phase, Charcot's foot can be difficult to distinguish from infection.

Clinical diagnosis of Charcot's foot is based on the appearance of a red, swollen oedematous and possibly painful foot in the absence of infection. It is associated with increased bone blood flow, osteopenia and fracture or dislocation; however the disease process can become quiescent with increased bone formation, osteosclerosis, spontaneous arthrodesis and ankylosis.³⁵⁶ Evidence level 2++

Acute Charcot's foot is associated with a skin temperature 2-8°C higher than the contralateral foot as measured on thermography.^{357, 358} Evidence level 3

There is insufficient evidence to recommend the routine use of magnetic resonance imaging or dynamic bone scanning to distinguish acute Charcot's from osteomyelitis.

Diagnosis of Charcot's foot should be made by clinical examination supported, where available, by the use of thermography.

Treatment of Charcot's foot in contact casting is associated with a reduction in skin temperature as measured by thermography and in bone activity as measured by bone isotope uptake compared to the normal foot.³⁵⁸ One follow up study showed that non-weight bearing and foot protection with therapeutic shoes resulted in a healing rate of 96% in patients with diabetic foot deformities.³⁵⁷ Evidence level 3

Total contact casting and non-weight bearing are effective treatments for acute Charcot's foot.

There is insufficient evidence to recommend the routine use of bisphosphonates in acute Charcot's foot, although case series involving small numbers of patients indicate that they may reduce skin temperature and bone turnover in active Charcot's foot.^{359, 360}