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Treatment of the Diabetic Foot

Essentials

  • Diabetes predisposes the patient to foot deformities, infections and ulcers.
  • The most significant causes of foot problems are neuropathy Diabetic Neuropathy and ischaemia Lower Limb Ischaemia associated with external injury.
  • Follow-up and early treatment prevent complications and amputation. Even minor skin injuries should be treated without delay.
  • A total-contact cast, therapeutic shoe or other offloading will help to treat chronic ulcers Treatment of Lower Extremity Ulcers.
  • Critical ischaemia Lower Limb Ischaemia should be recognized and treated immediately with vascular surgery.
  • An erythematous, hot and swollen foot in a patient with diabetes must be considered Charcot's foot until otherwise proven.

Examination of feet

  • The feet should be examined at least once a year, particularly in patients with type 2 diabetes and in patients with type 1 diabetes aged more than 30 years whose disease has been present for more than 15 years.
  • The examination can be performed by a chiropodist/podiatrist or a diabetes nurse specialist.
  • Poor glucose control, target organ damage, smoking, alcohol consumption, poor hygiene and mental problems predispose to foot problems.
  • Padding and positioning should be used to prevent the development of pressure ulcers in bedridden patients with diabetes. The skin should be checked daily.
  • Risk classification T1 helps to direct special attention and interventions to those who will benefit most (risk category 2-3).
  • The WIfI (Wound, Ischemia, and foot Infection) classification correlates with important clinical end points such as preservation of the extremity and healing of the ulcer http://iwgdfguidelines.org/wp-content/uploads/2019/05/IWGDF-Guidelines-2019.pdf.

Risk classification of diabetic foot problems

Risk category CriteriaTreatment and examinations
0
  • No loss of protective sensation
  • No lower extremity arterial disease
Annual assessment
Guidance on shoes and care of the feet
Training improving body control and strengthening the lower extremity (ankle and foot, in particular)
1
  • Loss of protective sensation or lower extremity arterial disease
Assessment every 6-12 months
Self-monitoring of feet
Guidance on shoes and care of the feet
Training improving body control and strengthening the lower extremity (ankle and foot, in particular)
2
  • Any of the following:
    • loss of protective sensation or lower extremity arterial disease
    • loss of protective sensation and structural changes in feet or functional changes in joints
    • lower extremity arterial disease and structural changes in feet or functional changes in joints
More intensive self-care
Training improving body control and strengthening the lower extremity (ankle and foot, in particular)
Sensation in feet should be tested at every visit unless there is a history of loss of sensation
Pulse palpation, with ABI, as necessary
Customised insoles or special shoes considered
3
  • Loss of protective sensation or lower extremity arterial disease and at least 1 of the following:
    • past or current history of foot ulcer
    • partial foot amputation
    • amputation above the ankle
    • end-stage kidney disease
Individual treatment and monitoring (foot health practitioner/chiropodist/podiatrist)
Intensified treatment and self-care
Training improving body control and strengthening the lower extremity (ankle and foot, in particular)
Customised insoles or special shoes considered
  • Neuropathy
    • Symptoms of sensory neuropathy include tingling, numbness, cramps, “restlessness”, lack of sensation, pain, and hyperaesthesia in the feet.
    • Weakened sense of touch (monofilament test, see picture ), disappearance of the sense of vibration (128 Hz) , and absence of the Achilles tendon reflexes are the most easily recognized signs of neuropathy Diabetic Neuropathy.
  • Circulation
    • Claudication, pain at rest, history of vascular surgery Lower Limb Ischaemia?
    • Cold feet and thin, shiny and erythematous or cyanotic skin suggest poor arterial blood flow.
    • If palpation of ankle pulses is uncertain, measure the ABI (see Doppler Stethoscopy in Diagnostics).
      • An ABI below 0.9 suggests occlusive arterial disease.
      • An ABI exceeding 1.4 suggests stiffening of the arterial wall due to media sclerosis, which may give erroneously high and unreliable ankle pressure readings (if so, toe pressure should be measured in specialized care).
      • Ankle pressure below 50 mmHg or, in case of tissue damage, below 70 mmHg, suggests critical ischaemia (pain at rest, ulcer, necrosis, see Lower Limb Ischaemia).
    • Autonomic neuropathy Diabetic Neuropathy increases arteriovenous shunting, which makes the foot feel warm to the hand and the veins full. However, in spite of seemingly good blood flow the oxygen supply of the tissues is decreased.
  • Changes in the skin, changes in nails, ulcers, macerations, blisters and infections
    • Thickening of the skin in the pressure areas
    • Calluses (the risk of an ulcer is high if there are dark haemorrhages in the callus)
  • Deformities (see also Figure 2 in http://iwgdfguidelines.org/wp-content/uploads/2019/05/IWGDF-Guidelines-2019.pdf)
    • Pes transversoplanus predisposes to a callus and ulcer in the middle of the ball of the foot.
    • Overlapping toes, hammer toes
    • Hallux valgus
    • Prominent metatarsal bone ends on the sole of the foot
    • Podoscopy or pedography will help in recognizing pressure sites.
  • The shoes and their fit should be examined.
    • Are the currently worn shoes worn daily or only occasionally?
    • Is the shoe big enough (length of the foot + 1-1.5 cm)? Are there bulges around the first and fifth toes? Where does the lining appear worn?
    • Are the socks of a suitable size and made of soft cotton?

Foot ulcer Dressings for Healing Diabetic Foot Ulcers, Negative Pressure Wound Therapy for Treating Foot Wounds in People with Diabetes Mellitus, Pressure-Relieving Interventions for Treating Diabetic Foot Ulcers, Debridement of Diabetic Foot Ulcers

  • Even minor injuries should be carefully treated and followed up.
  • A neuropathic ulcer arises at the site of a callus or corn.
    • Prescribe rest, crutches and reducing the number of steps
    • Alleviation of the pressure load is the most important treatment.
      • An offloading insole, a removable cast walker, therapeutic shoe etc.
      • The ulcer will heal in approximately 1-1.5 months with a total-contact cast. Cast treatment should be carried out in a unit with appropriate experience. Cast treatment is contraindicated in the following cases: deep infection requiring drainage, severe ischaemia, broken skin on the foot or leg, severe oedema of the foot, often also poor cooperation, poor vision, problems with balance and significant obesity.
  • Typical sites for an ischaemic ulcer are the tip of the toes, between the toes, at the lateral edge of the foot or on the heel. The surrounding skin is thin.
  • Remember the possibility of osteomyelitis in deep ulcers.

Topical treatment

  • Hyperkeratosis around a neuropathic ulcer must be mechanically removed, even every week.
  • Dry wound necrosis in an ischaemic limb should not be removed before vascular surgical procedures, unless there is pus underneath the eschar.
  • Otherwise, the principles for treating chronic leg ulcer should be followed; see Treatment of Lower Extremity Ulcers.

Antimicrobial treatment

  • A superficial, uncomplicated ulcer does not require routine antimicrobial treatment.
  • Antimicrobial treatment is indicated if infection is suspected.
  • Perform bacterial culture of deep pus samples (curettage, aspiration or biopsy) from the base of mechanically debrided ulcers.
  • If the patient has a diabetic infected ulcer and non-surgical treatment is considered, the duration of treatment depends on the severity and depth of the infection. See also locally available guidelines on antimicrobial therapy.
  • Mild, superficial infection 1-2 weeks
  • Moderately severe infection 2-4 weeks, provided that there is no osteomyelitis
  • Severe infection, most commonly 4-6 weeks, in the case of deep infections, e.g. osteomyelitis and cellulitis, see below.

Indications for hospital treatment / consultation

  • Fever or impaired general condition
  • Severe (critical) ischaemia
  • Deep ulcer possibly extending to the bone or the joint
  • Cellulitis more than 2 cm in diameter around an infected ulcer
  • Ulcer not showing clear signs of healing within two weeks. Pulses not palpable in the foot with the ulcer.
  • Patient unable to follow the advice for treating the ulcer, poor conditions for treatment at home.

Superficial fungal and bacterial infections

  • The diagnosis and treatment of fungal infections should be based on fungal culture, the sample collected from cleansed skin after any bacterial infection has healed; see Dermatomycoses.
  • Infectious (eczematoid) dermatitis (pictures ) is often preceded by a fungal infection.
    • Pustular erythema of sudden onset between the toes and on the metatarsus
    • Antimicrobial drug therapy targeted at staphylococci should be started as early as possible (e.g. cephalexin 500 mg 3 times daily).
    • Potassium permanganate baths (1:10 000) and, in the pustular phase, a cream containing a corticosteroid and an antibacterial agent, covered by a compress moistened with physiological saline. The compress should be changed or moistened every 4-6 hours. As the infection subsides, the dressings should be made less occlusive and drier to accomplish a "dry wound".
  • Paronychia in a patient with diabetes always requires serious attention. It is usually due to wrongly cut nails or tight shoes.
    • The patient should be instructed to cut the nails straight. A foot health practitioner/chiropodist/podiatrist can straighten the growth of the nail with a spring clip or some other device.
    • Antimicrobials (e.g. cephalexin 500 mg 3 times daily) may be indicated in the early phase.
    • Potassium permanganate baths. Neomycin and bacitracin should not be used because of the risk of allergy.
    • If paronychia becomes chronic, the edge of the nail should be cut and the nail root should be phenolized Paronychia and Ingrown Toenail. If the circulation in the foot is clearly impaired, the patient is referred to specialized care (the procedure cannot be performed under local anaesthesia).

Deep infections (osteomyelitis and cellulitis)

Osteomyelitis

  • An extensive (exceeding 2 × 2 cm2 ), deep ulcer (the bone can be detected at the bottom of the ulcer using a probe), fistula formation and copious secretion suggest osteomyelitis.
  • Probing and radiography are often adequate as primary examinations.
    • If the probe reaches the bone, treat the ulcer as if it were osteomyelitis.
    • If the probe does not reach the bone, an antimicrobial course should be given, as in soft tissue infections. Repeat radiography and evaluate the treatment response after two weeks. If osteomyelitis is seen on the radiograph or the ulcer is still secreting, the ulcer should be treated as osteomyelitis.
  • Changes become visible on the plain radiograph, at the earliest, after 2-6 weeks. MRI can be considered in case of strong suspicion.
  • CRP will increase in an acute infection. In chronic osteomyelitis, CRP is often normal and the erythrocyte sedimentation rate increased (over 70).
  • Do not hesitate to consult a specialist (invasive sampling for bacterial culture, MRI).
    • In the acute phase, treat with i.v. clindamycin 450 mg 4 times daily + oral ciprofloxacin 500 mg twice daily, for example.
    • The treatment can be continued with oral clindamycin 150 mg 4 times daily.
    • After clinical healing and closure of the ulcer the antimicrobial treatment should be continued for 1-2 months, sometimes even for years.

Cellulitis

  • Cellulitis with high fever, resembling erysipelas, should always be treated in hospital with i.v. antimicrobials.
    • In milder cases, the treatment is i.v. cefuroxime 1.5 g 3 times daily + oral clindamycin 150-300 mg 4 times daily in the primary care hospital ward. Intravenous ertapenem 1.0 g once daily is also an alternative. The treatment can be continued orally (clindamycin) after the fever has decreased and the infection has abated (CRP). The total duration of the antimicrobial treatment is 2-4 weeks.
    • Penicillin GErysipelas can be used in the treatment of mild erysipelas, if no diabetic neuro- or macroangiopathy is present in the patient's feet.
    • In severe cases, the treatment is imipenem or a third generation cephalosporin + clindamycin in a specialized care hospital.

Charcot's neuroarthropathy

  • This condition often involves rapidly progressing fragmentation of bones, joint injury, a predisposition to subluxation and luxation, and appears in a non-ischaemic foot of a patient with long-standing diabetes.
  • The first symptoms are oedema, mild pain, heat and sometimes redness of the foot.
  • Radiographic changes are visible in the late stage of the disease. A collapsed arch due to destruction of the TMT joints, resulting in a rocker-bottom foot, is typical. When needed, the diagnosis may be confirmed by MRI.
  • CRP and erythrocyte sedimentation rate are normal; plasma alkaline phosphatase may be increased.
  • The treatment is 3-9 months' immobilization with a cast and forearm crutches starting as early as possible. In the initial phase, a closed cast should be used.

Self-care and treatment of position deformities Patient Education for Preventing Diabetic Foot Ulceration, Prevention of Foot Ulcers in Diabetics

  • Good foot hygiene and regular application of ointment, careful treatment of the nails, prevention of fungal infections
  • Foot exercises and walking (but not barefoot in nature)
  • Avoiding artificial warming and even minor injuries
  • Prevention and regular removal of calluses and corns (Video Removing Clavus with Scalpel from Diabetic Foot Ulcer)
  • Suitable shoes, ready-made or customised orthopaedic shoes when needed
  • Offloading or biomechanical insoles
  • Orthoses, toe splints, toe padding
  • Surgical treatment: correction of hammer toes, bunion removal / straightening of toes, metatarsal resection
  • Provide the patient with locally relevant patient information.

References

  • Crawford F, Cezard G, Chappell FM et al. A systematic review and individual patient data meta-analysis of prognostic factors for foot ulceration in people with diabetes: the international research collaboration for the prediction of diabetic foot ulcerations (PODUS). Health Technol Assess 2015;19(57):1-210. [PubMed]
  • Zhan LX, Branco BC, Armstrong DG et al. The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing. J Vasc Surg 2015;61(4):939-44. [PubMed]
  • Tone A, Nguyen S, Devemy F et al. Six-week versus twelve-week antibiotic therapy for nonsurgically treated diabetic foot osteomyelitis: a multicenter open-label controlled randomized study. Diabetes Care 2015;38(2):302-7. [PubMed]

Evidence Summaries ⬆