US Pharm. 2013;38(3):13-14.
Nerve Damage Due to Diabetes
Peripheral neuropathy is damage to nerves in the
peripheral nervous system, the set of connections that link nerve
impulses between the central nervous system (brain and spinal cord) and
the outlying areas of the body. Although it is not entirely clear why
diabetes causes nerve damage, it is thought to be a result of poorly
controlled blood sugar over a long period of time.
There are three general types of nerves that can be
damaged in peripheral neuropathies—the sensory, autonomic, and motor
nerves. Diabetic peripheral neuropathy (DPN) that affects the sensory
nerves results in symptoms such as numbness, tingling, increased
sensitivity to touch, and burning in the feet, legs, hands, and arms.
When autonomic nerves are damaged, symptoms include problems with
digestion, breathing, vision, heartbeat, sexual function, and bladder
control. Motor nerve damage can be seen in patients with muscle
weakness, cramping, or twitching.
The best treatment for DPN is prevention, and tightly
controlling glucose levels is the key to success. It is important to
maintain a healthy diet, exercise regularly, and limit alcohol. Proper
foot care is essential to avoid infections. Nicotine constricts blood
flow to peripheral nerves, so smoking cessation is very important to
prevent the progression of diabetic nerve damage. Specific treatments
are available for individual types of neuropathies, including oral and
topical medications that ease pain, regulate blood pressure and heart
rate, improve gastric emptying time and digestion, and enhance urinary
and sexual function.
Regular Foot Care Is Essential to Prevent Infection
High blood sugar can lead to damage of the sensory,
autonomic, and motor nerves that play an important role in health. The
risk of nerve damage increases with time, so most of the health
consequences of long-term diabetes occur many years after diagnosis.
Eventually, more than half of all diabetics will have some degree of
peripheral neuropathy, although not everyone will suffer from its
symptoms. It is likely that high blood sugar, high cholesterol,
hypertension, and obesity contribute to the damage of peripheral nerves.
Types of Nerve Damage
Diabetic peripheral neuropathy (DPN) of the sensory nerves
signals a problem with the transmission of sensations between the brain
and the distant nerves of the arms and legs. A common symptom of
sensory nerve damage is numbness. When sensation is lost in the
extremities, especially the toes and feet, there is no warning of injury
or infection. Without proper foot care, this loss of sensation can
result in serious infections that require amputation. Another form of
sensory nerve damage involves increased sensitivity to touch, tingling,
pins-and-needles sensations, and burning, often beginning in the feet,
slowly moving up the legs, or progressing from the fingers to hands to
Autonomic nerve damage can affect a variety of
organs and their function. Difficulty swallowing, slowed stomach
emptying, constipation, and diarrhea are potential problems with
digestion that are controlled by autonomic nerves. The autonomic nerves
also control heart rate and blood pressure, so heartbeats may be too
fast or irregular, and dizziness can be a problem when standing up from a
sitting position. Patients with diabetes have a higher risk of
cataracts, glaucoma, and retinopathy, which can cause blindness. Other
conditions that result from autonomic nerve damage include problems with
bladder emptying and sexual function.
Motor nerve damage can be seen in the patients with muscle weakness, cramping, twitching muscles just under the skin, and paralysis.
Diagnosis of DPN is based on a thorough review of
symptoms, as well as a physical examination and testing to determine the
type of nerve damage and its severity.
Treatment and Prevention Options
Treatment of DPN depends on the type and severity of nerve
damage. Strict blood sugar control is the most important step toward
limiting the progression of nerve damage and preventing future
complications. Once blood sugar is in a normal range and diet, exercise
(or physical therapy), and medications are adjusted to maintain good
control over blood sugar fluctuations, treatment to help relieve
symptoms can begin.
Diabetic nerve pain is treated with antidepressant
medications, anticonvulsant drugs, and opioid painkillers. Drugs
specifically approved to treat the pain of DPN include duloxetine
(Cymbalta), pregabalin (Lyrica), and tapentadol (Nucynta). Skin creams
and transdermal patches are also available. Medications are also used to
improve stomach emptying, blood pressure, bladder control, and sexual
A serious complication of DPN is infection. Regular foot
care is very important in prevention and early treatment of infection,
which may be missed due to lack of symptoms and poor peripheral
circulation with advancing age. When a soft-tissue infection spreads to
the bone, amputation of the toes or foot may be required. Prompt
recognition of an infection and timely treatment can prevent many of
these surgeries. Patients with diabetes should have a foot examination
at least once a year to check for neuropathy. If a sensory neuropathy is
detected, more frequent foot examinations should be scheduled to assist
in early detection of infections, as well as their prompt treatment.
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