Peripheral neuropathy is the most common type of
diabetic neuropathy. It occurs when diabetes damages
sensory nerves, which allow the brain to respond to sensations like pain,
touch, temperature, and vibration. Peripheral neuropathy may also damage the
motor nerves, which work with the muscles to control movement.
The effects and symptoms of peripheral neuropathy develop slowly over
months or years. The first symptom is usually a slight burning sensation in the
affected area. If blood sugar levels remain high over several years, the
burning sensation greatly increases and then slowly goes away. It is replaced
by a complete lack of feeling and sensation, or numbness, making the person
more likely to injure the affected area.
Although peripheral neuropathy can develop almost anywhere in the
body, it most often affects the feet and legs. Loss of the protective
sensation—the reduced ability to feel pain—in the feet may lead to the
formation of calluses and blisters, bone and joint problems, infection, and
foot ulcers. For instance, small, repetitive injuries to the foot, such as
those caused by a poorly fitting shoe, may lead to bigger problems simply
because the person is unaware of them. Reduced feeling in the feet can also
alter a person's step, leading to bone or joint problems.
If untreated, foot problems can become so severe that the foot or
lower leg may have to be amputated.