D IABETES V IGNETTE
Diabetes Vignette
‘Microwave foot’: a new hazard for the diabetic
neuropathic foot
Diabetic foot ulceration is a major cause
of morbidity and amputation, often
leading to prolonged hospitalisation and
high health care costs.2–51hot
flagstones,Many ulcers are related to
sensory neuropathy, and are potentially
preventable. Neuropathic ulcers often
relate to unperceived trauma due to pedal
insensitivity. Occasionally, the trauma can
be thermal and reported causes include
barefoot walking on hot sand,6–94and
hot-water bottles.8hot-water footbaths
We have recently encountered two
patients with diabetic sensory
neuropathy, who developed significant
thermal ulcers as a result of the
self-application of warming pads or
bags containing gels or grain,
preheated in a microwave oven.
Figure 1. Right heel ulcer caused
by microwave-heated bag
required close surveillance in a diabetic
foot clinic, with prolonged antibiotics
and pressure-relieving footwear. The
ulcers healed eventually in 33 weeks.
Discussion
10These
two cases highlight an
unappreciated cause of thermally
induced foot ulceration in diabetic
patients with sensory neuropathy. In
both cases intensive podiatric care was
needed and, in Case 2, prolonged
multidisciplinary treatment was required
to achieve healing eight months after the
original injury. The two patients had
clearly ‘at risk’ feet, with past ulceration,
and current neuropathy. Interestingly,
both patients were known to our foot
Case 2. A 53-year-old man presented clinic, and had previously received
Case reports
Case 1. An 86-year-old man presented to with extensive ulceration of the lateral education on prevention of foot
border of the right foot (Figure 2). He
ulceration. Despite this, both patients
a diabetic foot clinic with a right heel
had type 2 diabetes of 20 years’
applied a heated device to their feet.
ulcer. He had type 2 diabetes of 12 years’
duration, had previous foot ulceration, Interestingly, failure to adhere to foot
duration, a previous history of foot
and was on insulin treatment with poor care advice has been previously noted
ulceration, and good glycaemic control
glycaemic control (HbA 1c 9.9%). Foot in diabetic patients who develop foot
(HbA 1c
pulses were impalpable, but audible
ulceration whilst on holiday in hot
6.9%) on gliclazide and metformin. The
with Doppler, and 10g monofilament
countries.
ulcer was superficial but large, measuring
sensation was impaired. The
78x49mm (Figure 1). Foot pulses were
ulceration had been caused by a
normal and 10g monofilament sensation
gel-filled microwaveheated bag used
was absent in both feet. The ulcer had
by the patient to relieve foot coldness
the appearance of a thermal burn, and
(Figure 2). There were four separate
had been caused by a
areas of ulceration, and he
microwave-heated, grain-filled bag
(Figure 1). This had been bought for the
patient by a relative, and had been used
in bed for the relief of cold feet. After the
first night’s use, the ulcer was discovered.
Regular podiatry care was needed, but
no antibiotics. It took 14 weeks to heal.
Though a number of thermal insults to
the diabetic neuropathic foot have
been recorded (hot-water bottles, foot
spas, hot flagstones etc), an extensive
literature search has revealed only one
similar case, recorded in the German
Figure 2. Extensive ulceration
resulting from microwave bag use
11literature.
This concerned a diabetic
patient with advanced complications
and on chronic peritoneal dialysis, who
used a seed-containing pad heated in a
microwave oven. This was applied to a
foot, resulting in extensive burns and
eventual amputation.
These devices offer a clear potential
danger to diabetes patients with sensory
neuropathy. The instructions on them areR Rowlands, Department of Podiatry
SJ Benbow, D Sharma, GV Gill*
often unclear, and their safe use
depends on a person’s ability to feel howDepartment of Diabetes/Endocrinology
hot the device has become. As
All at: Aintree University Hospitals NHS
microwave ovens have different levels of Foundation Trust, Liverpool, UK
power, heating can also be variable
*E-mail: g.gill@liv.ac.uk
between machines, compounding the
risk. Health professionals and patients References
need to be aware of this problem, and References are available at
such devices should carry a hazard
www.practical diabetesinternational.com.
warning for patients with diabetes.
Practical Diabetes International invites you to submit your favourite slide with clinical details for
possible publication in this series.
204 Pract Diab Int June 2010 Vol. 27 No. 5 Copyright © 2010 John Wiley & Sons
D IABETES V IGNETTE
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