Diabetes Cont Ed June 06/SM/RF/TH
MODULE 13:
19/05/2006
11:30
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Diabetes mellitus
GLOBALLY the incidence of diabetes is likely to exceed 250
million people by 2025 – that is a measure of the scale of the
problem this condition is likely to present in the future. It is
evidence of how diabetes will be one of the foremost public
health challenges facing the world in the decades ahead.
Accordingly diabetes belongs at the top of the healthcare
agenda, it has yet to be afforded that position.
Throughout 2006, this Continuing Education module will
PART 6
Diabetes and
foot disease
by Rita Forde
FOOT COMPLICATIONS are a significant cause of morbidity for
people with diabetes. Significant proportions of foot problems
associated with diabetes are actually preventable.1,2 Consequently
it is imperative that the person living with the condition fully participates in the care of their feet. A meticulous preventative
education programme is the ideal and for those with foot disease
a maintenance footcare programme is necessary.2
There is substantial evidence supporting an organised diabetes
footcare programme, as 40%-70% of all lower extremity amputations are related to diabetes.3 Additionally 85% of all diabetesrelated lower extremity amputations are preceded by a foot ulcer.
People can develop foot problems related to neuropathy, arterial
disease or infection. Any one element can be present and may
lead to cellulitis, ulceration or tissue necrosis.3
Preferably people with diabetes experiencing foot problems
should be cared for in combined specialist foot clinics. These clinics should have input from diabetes nurses, endocrinologists,
podiatrists, vascular surgeons, orthopaedic surgeons and orthotists. Unfortunately the availability of these clinics is extremely
limited. However, where established, a reduction in the rate of
lower limb amputations has been evident.3,4
Several pathological manifestations of diabetes contribute to
the development of foot disease. Foot lesions frequently result
from a combination of two or more of these occurring together.1
Components of foot problems
Neuropathy: This is the loss of sensory, motor or autonomic
neural function. It is the major contributing factor for 80% of foot
ulcers and lower limb amputations. It is classified as sensory,
motor or autonomic neuropathy.3,5,6
deal with the causes and complications of diabetes mellitus,
and the management of type 1 and type 2 in the various
patient groups.
This month Rita Forde outlines the impor tance of
preventative management in footcare.
Next month we will continue the focus on the complications
of the condition and how they can be prevented. This will
include microvascular and macrovascular complications.
Sensory neuropathy: This is the loss of protective sensation, leaving the foot vulnerable to injury. This can result in the foot being
exposed to isolated trauma, repetitive stress and injury, often due
to inappropriate footwear as sensation is blunted.3,5-7
Motor neuropathy: This results in the atrophy of pedal muscles
and fat pads, which protect the metatarsal heads and the plantar
surface of the foot. This may cause flexion deformity of the toes
and lead to an abnormal walking pattern. These in turn result in
altered pressure on the foot and the development of calluses.3,5-7
Autonomic neuropathy: This results in diminished sweating
which leads to dry skin and makes the foot prone to cracking and
breakdown of the skin. Altered blood flow leads to the distended
appearance of the veins, resulting in a warm foot that may be
numb with palpable pedal pulses.3,5-7
Charcot neuroarthropathy: This is a serious manifestation of
autonomic neuropathy, which leads to destruction of the foot
joints and results in severe foot deformities. This abnormality
necessitates the use of custom-made shoes, as the altered shape
of the foot is prone to trauma and ulcer formation.3,5,6,8
Ischaemia (peripheral vascular disease): Ischaemia results from
atherosclerosis of the leg blood vessels. In the person with diabetes it is usually bilateral, multisegmental and distal.3,5,7,8
Neuro-ischaemia: This is a combination of both neuropathy and
ischaemia and is often present in people who have diabetes.3,5-7
Neuropathic ulcer: This usually occurs on the plantar surface of
the foot. Foot deformity may be present which leads to prominent metatarsal heads and claw toes. There is the formation of
callus and the ulcer, which lies beneath, is painless and there may
be evidence of infection such as cellulitis or osteomylitis.3,5,6,8
Ischaemic ulcer: An ischaemic ulcer usually occurs on the margins of the foot or the tops of the toes. The person with this type
of ulcer complains of pain which may be severe and the foot is
cold to touch. There may be evidence of infection or a dry
necrosed area may be present.3,5,7,8
Foot examination
A review or assessment of a person with diabetes is incomplete
if a thorough foot examination is not included, regardless of their
presenting illness.1 Ideally a foot examination and screening
should be carried out by healthcare personnel with knowledge
and experience in caring for people with diabetes.3 However the
reality is that people living with diabetes are cared for by a variety
of healthcare professionals.
A comprehensive examination should include a review of the
This module is supported by Sanofi Aventis
Diabetes Cont Ed June 06/SM/RF/TH
19/05/2006
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Continuing Education
person’s general medical and surgical history, diabetes history, previous foot problems, inspection and palpation of the feet, and the
ordering and interpretation of relevant laboratory investigations.5
History
The review of the person’s history should encompass any previous foot related problems such as neuropathy, foot deformity or
previous callus formation.9 In addition any reported impairment
of the protective sensation in their feet, reduced or absent pedal
pulses or previous foot ulcer or amputation should be noted.
Other components of the review are the person’s glycaemic
control, smoking status, present drug treatment and the presence
of other conditions such as abnormal lipid levels, hypertension
or claudication of the limbs.2,3 The person’s self care behaviour and
knowledge is also crucial as this is an indicator of their capacity to
be involved with their management.1
Foot inspection
Foot inspection is probably the most important aspect of footcare for people with diabetes.3 When looking at the feet one
should consider the shape, colour and overall condition. The
shape of the feet and toes is a cue for diabetes-related conditions.
The loss of the plantar arch or a charcot foot are major indicators
of neuropathy.7 Other deformities such as hammer toes or claw
toes are also cues for this.3,7 Callus formation indicates chronic
high foot pressure over the metatarsal heads during normal gait,
which is an indicator for neuropathy.5
The location of the ulcer is an indicator of the type of disease.10
Neuropathic ulcers are generally located on the plantar aspect of
the foot under the metatarsal heads or on the plantar aspect of
the toes. Conversely ischaemic ulcers are usually located on the
margins of the foot. Features such as dry or hairless skin, callus
formation, necrosis or oedema are all specific indications for
neuropathy, ischaemia or neuro-ischaemia.3
Foot palpation
When assessing the temperature of a limb the back of hand
(not palm) should be used.11 Neuropathic feet tend to be warm to
touch with bounding pulses, while a cool limb with shallow or
absent pulses is indicative of an ischaemic foot.3 The temperature
must be compared in an ascending manner towards the knees,
which will alert the assessor to variances. Both feet should be
assessed and compared.11
Palpation of the pulses is mandatory when assessing the feet.
Initially the assessor should locate the dorsalis paedis and posterior
tibial pulses. If these are not palpable the popliteal and femoral
pulses should be palpated.The dorsalis paedis pulse is congenitally
absent in a small number of people.
A specialist foot review also encompasses both a neurological
and vascular assessment. For many people with diabetes a combination of neurological and vascular disease may be present and is
referred to as neuro-ischaemia.
Neurological examination
Symptoms of peripheral neuropathy include burning or stabbing pain, paresthesia or hyperesthesia which are all prone to
nocturnal exacerbation.3 Signs of neuropathy include reduced
sensation to pain, temperature and vibration, small muscle
wasting, absent sweating and distended dorsal foot veins.
Sensory loss is a major predictor of foot ulcers, thus periodic
neurological examination of the feet of people with diabetes is
essential. While expensive equipment is available for conducting
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WIN June 2006
these examinations, vibration is tested using a 128Hz tuning fork
and sensation is assessed using a 10g monofilament. 1 These are
the tests of choice due to their simplicity, low cost and semi-quantitative determinants of neuropathy. In addition ankle and knee
reflexes can be tested using a tendon hammer.
Vascular examination
Peripheral vascular disease is the most important factor related
to the outcome of a foot ulcer in people with diabetes and is a
major risk factor for lower extremity amputation.1 A vascular
examination commences with visual inspection of the feet.
The colour of the feet is an indicator of vascular status and
palpation of the pedal pulses is essential. An objective measurement of vascular status is the ankle brachial pressure index (ABPI).
The ABPI is measured by calculating the systolic ankle blood pressure divided by the systolic arm blood pressure.
Other more complex examinations are available in some
specialist centres.3 In particular angiography and magnetic resonance angiogram (MRA) are useful for diagnosis and determining
the extent of vascular disease.
Prevention
Many foot problems associated with diabetes can be prevented. A fundamental aspect of this is education – which should
be simple and repetitive and targeted at both healthcare professionals and people living with diabetes.
Inspection of the feet at regular intervals is imperative and
those identified with ‘at risk’ feet should have very frequent
reviews.5 Education in relation to appropriate footwear is crucial
as trauma can result from ill-fitting or unsuitable footwear. Ideally
new shoes should not need to be ‘broken-in’ and slip-on shoes are
not recommended. Home remedies,‘bathroom surgery’ and overthe-counter corn plasters are strongly discouraged.3 Should
treatment be necessitated, people with diabetes are advised to
attend a podiatrist for professional assistance.
Education
Information on footcare management should be encompassed
in all diabetes education programmes. It is an element of diabetes
care where the person living with the condition can have a direct
impact.5
Simple leaflets have been developed as a guide, which are useful for both patients and the healthcare professionals. Important
components include advising the person never to walk barefoot,
a simple but effective measure to avoid unnecessary risk to the
feet. Encourage people to develop a daily foot hygiene routine.
This should include inspection of feet when they are washing
them and ensuring that between their toes are completely dried
and then a moisturiser should be applied avoiding this area
between the toes. Toenails should be cut straight across avoiding
the creation of sharp edges. Home treatment for corns or calluses
is strongly discouraged; if these are present they need to be
treated by a podiatrist.
Shoes and stocking should be checked prior to wearing to
ensure that no objects have fallen into them.These should be correctly fitting to elude injury to the feet. All people with diabetes
are advised about the warning signs of foot problems and
encouraged to seek help early if they are concerned.
Rita Forde is advanced nurse practitioner – diabetes at the Mater Misericordiae
University Hospital, Dublin
References on request from [email protected] (quote: Forde R.WIN 2006; 14(6): 43-44)