Neuropathy is nerve damage which can be the result of numerous conditions. Diabetic neuropathy is nerve damage caused by diabetes which is long-term elevated levels of blood sugar. The extent of the damage can correspond to the average blood glucose levels and the length of time cells in the body have been exposed to it.
Definition & Facts
Diabetic neuropathy occurs in three ways. The first to normally occur is peripheral neuropathy. This is damage to the peripheral sensory nerves of the body. It typically presents as damage to the nerve fibers that sense touch in the fingers and toes. It can worsen to the point where so much feeling is lost in the feet that the patient does not notice when a sore on the foot is developing. Due to corresponding compromised blood circulation, a small sore can quickly develop into a major ulceration that does not heal and may lead to amputation.
Autonomic neuropathy affects the nerves that control automatic functions from heartbeat regulation to digestion. Gastroparesis is nerve damage to the stomach, and it is an example of autonomic neuropathy.
Symptoms & Complaints
Fingertips can have the sensation of a limb that has "fallen asleep." Some describe it as a full feeling in the fingers as if they are made of lead. As it progresses in the feet, pain sensation caused by impacts, cuts, penetrating objects and burns may not be felt at all. The lack of sensory feedback can lead to falls and dropping objects.
Proximal neuropathy can lead to muscle wasting and the inability to stand or walk without assistance. Autonomic neuropathy symptoms vary depending on which organ is affected. If it is the heart, then cardiac arrhythmia can develop. If the stomach or intestines are affected, then food can stay in the stomach too long. This can lead to vomiting. Intestinal involvement can cause a host of symptoms from severe constipation to painful spasms.
The main culprit in all cases of diabetic neuropathy is elevated blood glucose levels. When the body has excess glucose in circulation, it is called hyperglycemia. Glucose is the fuel used by the body to function. All food is eventually converted to glucose to be burned as fuel. Diabetics have problems with insulin which unlocks the cells to receive the glucose.
Type 1 diabetics lack insulin, and Type 2 diabetics have insulin resistance. Over time, Type 2 diabetics can become Type 1. Glucose alcohols dissolve the protective insulation, called myelin, around nerve fibers. The insulation around nerves is like insulation on wires that prevents short circuiting. As it dissolves, the nerves cannot conduct signals correctly. Major nerves, such as the vagus nerve, control everything from the heartbeat to digestion.
Diagnosis & Tests
Nerve conduction tests use sensors and needles to test nerve fibers and how they conduct signals. A similar test is electromyography. The test can be painful to some as the electrical impulses are generated to conduct the test.
One of the initial tests is using a piece of monofilament to determine if patients can feel it touching their toes and feet. This test is called the Semmes-Weinstein monofilament test. This test involves a small piece of monofilament which is used to touch the skin. It is not painful. Some doctors may use a pin prick to test for sensation. Diagnosis is made when there are clinical signs of reduced sensation and corresponding diabetes. Proximal neuropathy is difficult to diagnose, and electromyography can be used.
Gastroparesis is usually diagnosed by eating a small amount of a food prepared with a radioactive substance. The food is then tracked for how fast it moves out of the stomach through an imaging device that picks up the radioactive signal. Other gastrointestinal tract nerve damage may be diagnosed with varying tests from ultrasounds that use sound waves to see the organs to manometry that measures pressure.
The standard test for the level of control diabetics are achieving with their treatment regimen is the hemoglobin A1c test. This blood test shows the average blood glucose level over the last three months. The result corresponds with an average for how high the blood glucose level was, and it is measured in mg/dl. The American Diabetes Association recommends A1c results no higher than 7, which corresponds to a blood glucose average of 154 mg/dl. Some doctors recommend an A1c no higher than 6, which corresponds to an average blood glucose level of 126 mg/dl.
Treatment & Therapy
Selective serotonin reuptake inhibitors and other drugs, such as pregabalin, are being used to treat the pain of peripheral neuropathy. Proximal neuropathy is treated with painkillers and physical therapy. Corticosteroids are also sometimes used in the treatment of proximal neuropathy. Physical therapy is a big component of regaining strength in the legs of those suffering with proximal neuropathy due to diabetes in order to walk again.
Symptoms of gastroparesis can be mitigated by eating smaller and more frequent meals. Medications used to treat gastroparesis include metoclopramide and erythromycin. Both stimulate gastric motility. Erythromycin is also an antibiotic. Both drugs have the potential for serious side effects. Metoclopramide can cause tardive dyskinesia, which is uncontrolled movements, and erythromycin can cause heart arrhythmia in some people.
Prevention & Prophylaxis
There is hope of improving damage and symptoms caused by diabetic neuropathy. The best treatment is prevention. It follows the old adage of an ounce of prevention being worth a pound of cure. Control of blood glucose levels on a daily basis that result in long-term control is best. Lower A1c results are the goal, but daily control must also be sought. It is important to visit a healthcare professional any time when diet, exercise and medications are not providing good daily control of blood glucose levels.