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Preventing foot problems in people with diabetes

The end result of foot complications in diabetes is often amputation. Roger Gadsby outlines the signs and symptoms of diabetic foot problems and the invaluable role of the primary care nurse in detecting an at-risk foot

Roger Gadsby
BSc MB ChB DCH DRCOG FRCGP

GP Nuneaton Associate Clinical Professor
Warwick Medical School
University of Warwick
Dr Gadsby was a member of the Guideline Development Group for the NICE 2004 guideline entitled Prevention and Management of Foot Problems in People with Diabetes

Foot problems in people with diabetes result from microvascular and macrovascular complications such as peripheral vascular disease and neuro-pathy, which leads to loss of protective pain sensation in the feet.(1)
Between 20% and 40% of people with diabetes are estimated to have neuropathy depending on how it is defined and measured, and about 5% suffer from a foot ulcer, including plantar ulcers, toe ulcers, heel ulcers and so on.(1) Foot ulcers, if they do not heal, may lead on to amputation. A study in the Tayside area of Scotland showed that the incidence rate of diabetes-related lower limb amputation was 248 per 100,000 person years, which is 12.4 times higher than for the general population.(2)
Diabetic peripheral neuropathy is often symptomless, and the patient usually doesn't perceive the gradual loss of protective pain sensation as it develops. Thus there are people with diabetes with risk factors for foot ulceration and hence amputation.
Approximately 50% of people with diabetes who attend dedicated foot clinics have neuropathy and some degree of reduced blood flow resulting from generalised atherosclerosis, which produces tissue ischaemia in the foot.(3) Pure ischaemia without neuropathy is rare. Poor glycaemic control, duration of diabetes, and adverse socioeconomic conditions are other factors associated with increased risk of foot ulceration. The other 50% only have from neuropathy.
Feet that are at-risk due to neuropathy or ischaemia do not spontaneously ulcerate. Minor trauma is usually the additional factor that precipitates ulceration. Loss of protective pain sensation due to neuropathy may cause trauma through thermal damage (eg, walking on hot sand on holiday), chemical damage (eg, use of corn-cures), or through mechanical trauma (eg, tight fitting shoes, or standing on a stone or drawing pin).
Foot ulcers are susceptible to infection, which may spread rapidly causing overwhelming tissue destruction. This process is the main reason for amputation.
The presence of bony abnormalities in the foot, such as overriding toes, bunions, hallux valgus and hallux rigidus, increases the risk of trauma and is therefore an additional risk factor for ulceration. These areas of bony abnormality are often associated with the presence of callus (an area of dry, hard, often fissured skin) that is related to the increased pressure on that area of skin from the bony abnormality.

Preventing neuropathy and peripheral vascular disease
Smoking increases the risk of developing peripheral vascular disease and worsens if present. Therefore advice on how to quit is very important in anyone with diabetes who is smoking.
Evidence from randomised controlled trials in both type 1 and type 2 diabetes have shown that intensive control of blood glucose (giving HBA1c measurements of 7% or less) reduces the risk of the development of neuropathy. Good glycaemic control therefore reduces the risk of foot ulceration through reducing neuropathy.(4,5)
Trials have also shown that the use of statin therapy in people with diabetes as primary prevention reduces the risk of developing cardiovascular disease. The majority of people with diabetes are now being offered treatment with a statin such as simvastatin 40 mg. This may reduce the development of peripheral vascular disease, but this is not yet clear.

Prevention in primary care
An annual examination of the feet of every patient with diabetes needs to be undertaken.
People with diabetes need to be advised that they will be having an annual foot examination so they are prepared to take their shoes and socks off.

The annual foot examination
Inspect the foot for bony abnormalities. If bony abnormalities are present the foot is at risk. The commonest abnormalities are:

  • Bunions.
  • Overriding toes.
  • Hallux rigidus.
  • Hallux valgus.

Palpate for the posterior tibial and dorsalis pedis pulses. If they are absent the foot is at risk.
Detect the loss of protective pain sensation by using a 10 g nylon monofilament. Apply the filament to at least five sites on the foot (but not over callus) until it buckles, which occurs at 10 g of linear pressure when the patient is asked to detect its presence. If it cannot be felt, protective pain sensation is lost and neuropathy is present.

Classification of risk
People should be classified as at-risk if they have either inability to feel the 10 g nylon monofilament and/or absent pulses and/or foot deformity. People with two risk factors are more at risk, and those with all risk factors are most at risk.(1)

Referral for those with at-risk feet
Those with any risk factor need to be referred to the local "foot at risk clinic", run by the podiatry service to receive extra foot care education, further assessment to determine degree of risk and appropriate follow-up.(3)

Caring for "normal" feet
People with diabetes whose feet are not at risk need an annual foot examination and advice about self-care and monitoring, which should cover:

  • Daily examination of the feet for problems: colour change, swelling, breaks in the skin, pain or numbness.
  • Footwear: the importance of well-fitting shoes and hosiery.
  • Hygiene: daily washing and careful drying.
  • Nail care: they can cut or file their nails or have this done by their carer.
  • Dangers associated with practices such as skin removal (including corn removal).
  • Methods to help self-examination/monitoring (eg, the use of mirrors if mobility is limited).

What happens at the "foot at risk clinic"?
The podiatrist working at the "foot at risk clinic" will have experience and expertise in diabetes foot care and will further examine the feet to determine the level of risk. This may include the use of Doppler examination for blood flow, more detailed assessment of neuropathy and foot pressure measurements to detect areas of increased pressure.
They will also provide additional education and arrange appropriate review and follow-up every one to six months depending on the level of risk detected.
People with at-risk feet should address all the points of education for those with "normal" feet, but in addition need to consider the following:

  • If neuropathy is present, the resulting numbness means that problems may not be noticed, so extra care and vigilance and additional precautions to keep feet protected are needed.
  • Not walking barefoot.
  • Seeking help to deal with corns and callus.
  • Dangers associated with over-the-counter preparations for foot problems (eg, the danger of corn cures).
  • Potential burning of numb feet, checking bath temperatures, avoiding hot water bottles, electric blankets, foot spas, and sitting too close to fires.
  • Moisturise areas of dry skin.
  • Regular checking of footwear for areas that will cause friction or trauma.
  • Seeking help from a healthcare professional if footwear causes difficulties or problems.
  • Wearing specialist footwear that has been prescribed or supplied.
  • Consider the use of Polymer Gel podiatry products to protect specific areas on the foot.
  • Additional advice about foot care on holiday: not wearing new shoes; planning adequate rest periods to avoid additional stress on feet; if flying, walk up and down aisles; use of sun block on feet, especially on dry skin; bring a first-aid kit and cover any sore places with sterile dressing; seek help if problems develop; and holiday insurance issues (ensure diabetes cover).

Prevention in secondary care
The NICE guidelines recommend that people should be referred to a specialist multidisciplinary diabetes high-risk foot care team within 24 hours if any of the following occur:(1)

  • New ulceration (wound).
  • New swelling.
  • Discoloration (redder, bluer, paler, blacker over part or all of foot).

The specialist team, as a minimum, would be expected to:

  • Investigate and treat vascular insufficiency.
  • Initiate and supervise wound management, using dressings and debridement as indicated.
  • Use oral antibiotics for simple infection or systemic antibiotics for cellulitis or bone infection as indicated.
  • Ensure an effective means of distributing foot pressures, including specialist footwear, orthotics and casts.
  • lTry to achieve optimal glucose levels and control of risk factors for cardiovascular disease.

Most hospitals now have such foot care teams, which are often coordinated by a podiatrist with special interest in diabetes. It is vital that all healthcare professionals looking after people with diabetes know how to access this team in the emergency situation of discovering a new foot ulcer. They should contact the team straight away and get the person seen ideally within the NICE recommended timescale of 24 hours.

References

  1. National Institute for Health and Clinical Excellence. Prevention and management of foot problems in people with type 2 diabetes. London: NICE; 2004.
  2. Morris AD, McAlpine R, Steinke D, et al. Diabetes and lower-limb amputations in the community. A retrospective cohort study. DARTS/MEMO Collaboration. Diabetes Audit and Research in Tayside Scotland/Medicines Monitoring Unit. Diabetes Care 1998;21:738-41.
  3. Gadsby R, McInnes A. The at-risk foot: the role of the primary care team in achieving St Vincent Targets for Reducing Amputation. Diabetic Med 1998;15:S61-4.
  4. Diabetes Control and Complications Trial Research Group. The effect of intensive treatment on the development and progression of long term complications in insulin dependent diabetes mellitus. N Engl J Med 1993;329:977-86.
  5. United Kingdom Prospective Diabetes Study UKPDS 33. Intensive blood glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes. Lancet 1998;352;837-53.