Every year, burn units see people with diabetes who used a heating pad or hot water bottle on cold, aching feet and didn’t feel the damage happening. The wound can take months to heal, and sometimes doesn’t.
If you have diabetes, this is the one article on this site to read before you use a heat pad.
Why diabetes changes things
Two problems stack up.
- Nerve damage (neuropathy). High blood sugar over years damages the small nerves, starting furthest from the heart: toes, then feet, then lower legs. Those nerves carry the warning that something is too hot. Without them, skin can reach burning temperature while it still feels pleasantly warm.
- Reduced circulation. Blood flow carries heat away from warmed skin. When the vessels in the legs are narrowed, that cooling system works less well, so heat builds up faster. Poor circulation also means any burn heals slowly and is more likely to get infected.
Together they mean a setting that is comfortable for someone else can cause a deep burn on your foot without you noticing until you see it. The mechanism is the same one behind toasted skin syndrome, only faster and deeper.
The rules
- Never use a heat pad, hot water bottle or heat patch on your feet or lower legs. Not on low, not for five minutes. Warm socks instead.
- Never use heat anywhere you have numbness, tingling or reduced feeling.
- Never sleep with a pad on. See is it safe to sleep with a heating pad on?
- Never use heat on broken skin, an ulcer or a wound.
Where heat can still be reasonable
Diabetes doesn’t rule out heat everywhere. On an area where your sensation is completely normal, such as the lower back or shoulders in someone whose neuropathy is confined to the feet, a heat pad can be used with extra care:
- Check the sensation first. Ask someone to touch that area lightly with something warm and something cool while your eyes are closed. If you can’t reliably tell the difference, don’t use heat there.
- Lowest setting only, with the cover on plus a layer of clothing.
- 10 minutes, not 20. Use a timer.
- Look at the skin afterwards, every time. Even light pink means turn it down further.
- Ask your doctor or podiatrist first, particularly if you’ve had diabetes for many years.
Other ways to warm cold feet
- Loose, warm socks, including in bed
- Moving: a short walk warms the feet from the inside and helps circulation
- Raising the room temperature rather than heating one body part
- Blankets over the lap
More on this in cold hands and feet, which covers the non-diabetic causes too.
If you soak your feet, test the water with your elbow or a thermometer, never your feet, and keep it below body temperature range rather than hot.
See a doctor promptly if…
- You find a blister, redness, a raw patch or any new wound on your foot, however small
- Skin is broken, weeping or smells
- You have new numbness, burning or pins and needles in your feet
- A foot is pale, cold and painful
Foot wounds in diabetes are treated urgently for good reason. Don’t wait to see if it settles over the weekend.
Full list of who should avoid heat: who should not use a heating pad. If you’re helping an older parent, also read heat for back pain in older people.
The heat pad we use
We’ve supplied the Bremed BD7800 since 2010. It holds a steady temperature, covers a whole lower back and has a machine-washable cotton cover. Physiotherapy clinics in Singapore use it with their patients.
Clinically reviewed by: Nigel Chua (Hand Occupational Therapist) & Louise Yow (Physiotherapist). This article is general information, not a diagnosis. electricheatpad.com sells electric heat pads.
