The diabetic foot
Foot ulceration is a common complication of diabetes, which, if not detected early, can ultimately result in amputation.
The peripheral neuropathy and peripheral arterial disease which cause this complication can be delayed through strategies
targeting; glycaemic control, reduction of hypertension and blood lipid levels, smoking cessation and weight management.
Other factors which increase the risk of a person with diabetes developing foot complications include:3
- Previous foot ulceration
- Co-existing abnormalities of the foot
- Plantar callus
- Age over 70 years
- Pacific or Māori ethnicity
- Long duration, or poor control of diabetes
- Retinopathy or other diabetic complications
- Renal impairment
- Wearing inappropriate footwear
- Inability to maintain foot hygiene and prevent trauma
- Living in a lower socioeconomic area
People with diabetes should have their feet checked at least once every year, or more regularly (every three to six
months) if there is an increased risk of complications developing. Patients should also be encouraged to check their own
feet, or to enlist the help of a family member. Treatments which reduce foot pressure, including callus debridement, shoe
inserts and specialised footwear all reduce the risk of ulceration.2
There are two broad types of “diabetic foot”:4
- Neuropathic feet which are generally warm, dry and numb with a detectable pulse. The most common
complications are neuropathic joints and neuropathic ulcers which occur mainly on the soles. Minor lesions, such as blisters,
can develop into chronic ulcers which progress due to a lack of sensitivity in the foot.
- Neuro-ischaemic feet are frequently cold with no detectable pulse. Complications may include those
described above and intermittent limping, pain at rest and gangrene. Ulcers from pressure damage are generally found
on the edges of the feet.
Foot checks should begin as soon as a person has a confirmed diagnosis of diabetes and should include a visual inspection
for: redness, swelling, ulceration, deformity, tinea pedis, vulnerable pressure sites, poor self-care (lack of cleanliness
and untrimmed nails) and skin abrasions. The foot should be checked to see if joint movement is fixed or flexible. Ask
the patient if they have trouble walking or experience pain (burning or tingling) and what the normal temperature of the
foot is. Peripheral neuropathy can be assessed with a monofilament (touch pressure-testing) and by testing vibration sensation
with a biothesiometer or tuning fork. Peripheral circulation can be checked through palpation of pedal pulses. Evidence
of neuropathy and an absence of pedal pulse elevate the risk of ulceration, while additional skin changes and deformity
place a person at high risk of ulceration. It is important to remind people with diabetes of the importance of appropriate
footwear and foot hygiene at every oppurtunity.4,5
Diabetic foot ulcers should be cleaned, debrided (if appropriate) and covered with a dressing able to absorb any exudate
without plugging the lesion. Pain management should be given where appropriate. The foot should be rested and therapeutic
footwear worn while the lesion is healing. Regular assessments should be made until the ulcer heals, followed by checks
every one to three months. Urgent referral (within 24 hours) should occur if:
- An ulcer shows no sign of healing or becomes necrotic
- Significant swelling or discolouration of any part of the foot is present
- There is suspicion of bone or joint complications
If the wound appears infected, oral antibiotics can be prescribed initially. Infected foot ulcers are often colonised
by a variety of organisms, therefore a broad spectrum antibiotic such as amoxicillin clavulanate is appropriate.6 Refer
to a podiatrist or vascular specialist if complications develop, or if there are any concerns. Patients with extensive
infection, or who are systemically unwell should be referred to hospital for IV antibiotic treatment. It is important
to refer the patient for radiological assessment if osteomyelitis is suspected.
For further information see: “Screening
and management of the ‘diabetic foot’”, BPJ 31 (Oct, 2010)
Loss of vision due to diabetic retinopathy is a preventable complication that affects many adults with diabetes in New
Zealand. Primary care plays an important role in ensuring that people with diabetes receive regular retinal screening
and prompt treatment before visual deterioration begins. Estimates suggest that 30% of people with diabetes have some
degree of retinopathy, with 10% having sight-threatening retinopathy.7 The longer a person has diabetes, the
greater the chance they will develop retinopathy.
Diabetic retinopathy is generally asymptomatic, until it reaches an advanced stage which is often beyond treatment.
Early detection and prevention are the key responsibilities of primary care and are best achieved through:
- Ensuring retinal screening occurs at least every two years
- Improving glycaemic control and reducing high blood pressure and lipids
A referral for retinal screening should be made at the time a diagnosis of diabetes is confirmed. Screening should occur
more frequently for people showing early signs of retinopathy. As diabetic retinopathy can progress rapidly during pregnancy,
women with diabetes who are pregnant should be screened in the first trimester of their pregnancy. The goals of screening
are to identify people with early microvascular disease to allow optimal management of risk factors, and to refer those
with significant retinopathy to specialist care.
DHBs have individual arrangements with local retinal screening providers – contact your local DHB for details.
Managing the risk of retinopathy in people with diabetes can be achieved by:
- Maintaining good glycaemic control with an individualised HbA1c target
- Reducing blood pressure to ≤ 130/80 mm Hg3
- Reducing blood lipid levels towards a total cholesterol target of < 4.0 mmol/L8
- Smoking cessation, exercise and a healthy diet
For further information see: “Screening
for diabetic retinopathy in primary care”, BPJ 30 Aug, 2010).