Neuropathy, or nerve damage, is a serious and common complication of diabetes. Studies estimate that 50% of people with diabetes will develop neuropathy. Even if you lack symptoms—which is very likely, considering that many diabetics develop nerve damage one or two decades after diagnosis—you should maintain close control over blood glucose levels to keep your risk of nerve damage as low as possible.
In addition to keeping glucose levels in a healthy range, studies now show that controlling blood pressure to ward off complications from diabetes is just as important. In 2010, the British Medical Journal reported, “In patients with type 2 diabetes the risk of diabetic complications was strongly associated with raised blood pressure.” Any reduction in blood pressure is likely to reduce the risk of complications, with the lowest risk being in those with systolic blood pressure less than 120 mm/Hg.
Diabetic neuropathy is often caused by years of high, unregulated blood glucose, largely due to lack of awareness. Long periods of elevated blood glucose can injure the vessels that supply the body’s nerves with adequate nutrition and oxygen. After years of deprivation due to poor blood replenishment, the nerves become numb. Some people with neuropathy experience pain, but as the disorder progresses, that pain often disappears; the nerves are too damaged to feel anything.
Four Types of Neuropathy
Neuropathy is an umbrella term for several types of nerve damage. Peripheral neuropathy is nerve damage that affects the feet, toes, legs, hands, and arms. Autonomic neuropathy relates to damage of the nerves that regulate digestive, bladder, and bowel functions as well as heart and sexual function. Proximal neuropathy causes nerve damage in the thighs, hips, and buttocks. Focal neuropathy is the sudden weakness of one or more groups of nerves anywhere in the body.
In type 2 diabetics, nerve damage due to peripheral neuropathy usually affects the feet and legs before the arms or hands. Symptoms are varied and can be mild to severe. They include numbness, tingling or burning sensations, extreme sensitivity to touch, insensitivity to hot and cold temperatures, and pain or cramping. Some people with neuropathy are affected by their symptoms largely at night.
Peripheral neuropathy can cause muscle weakness and the loss of reflexes, which often leads to changes in a person’s mobility, gait, and balance. Changes in walking sometimes causes foot deformities and foot injuries. Risks from foot injuries are especially dangerous to diabetics since the combination of neuropathy and poor blood circulation makes wounds tougher to heal. Longer healing times can leave injuries prone to infection. In extreme cases, infection can lead to amputation.
In this type of nerve damage, the “automatic” nerve responses of the body’s internal organs are affected. Type 2 diabetics with autonomic neuropathy may have problems digesting food, breathing, trouble urinating or with incontinence, and/or sexual problems, such as impotence. Even the sweat glands and eyes can be weakened. Symptoms are varied and also range from mild to severe.
Problems with autonomic neuropathy may make it difficult to determine when your blood glucose levels are too low. Normally, symptoms associated with hypoglycemia like sweating and heart palpitations are obvious, but those symptoms may be masked by nerve damage. Because autonomic neuropathy often obscures the normally painful symptoms of a heart attack, those with the condition are urged to know the other warning signs, such as profuse sweating, pain in the arm, back, neck, jaw, or stomach, shortness of breath, nausea, and lightheadedness.
Nerve damage to the digestive system may cause constipation, trouble swallowing, or gastroparesis, a disorder that causes a delay in digestion. Gastroparesis may worsen over time until a person is debilitated by frequent nausea and vomiting. Delayed digestion often makes keeping track of glucose levels more difficult. In severe instances of gastroparesis, a person may subsist on a liquid diet or be fed via feeding tube.
Nerve damage to the cardiovascular system can cause changes in a person’s heart rate and blood pressure. For instance, type 2 diabetics with autonomic neuropathy may experience a drop in blood pressure after sitting or standing, causing them to feel dizzy and light-headed.
Nerve damage to the urinary tract and sex organs can cause difficulty controlling urination and sexual function. For instance, neuropathy in the bladder may cause incontinence or make it more difficult to fully empty. Autonomic neuropathy may also decrease sexual function, leaving men without the ability to become erect or ejaculate normally, and women with vaginal dryness and difficulty achieving orgasm.
This type of neuropathy commonly affects type 2 diabetics, especially older adults. It predominantly affects the hips, thighs, buttocks, or legs and typically begins on one side of the body. Proximal neuropathy can weaken the legs, and in severe cases, a person may lose enough muscle tone to no longer have the ability to go from a sitting to a standing position without assistance. Nerve damage of this type is often painful.
The head, upper body, or legs may be affected by focal neuropathy, which appears suddenly and is usually painful. Unlike the other forms of neuropathy, this type usually goes away in a few weeks or months and leaves no lasting damage.
Symptoms of focal neuropathy include an inability to focus, double vision, aching behind the eyes, one-sided facial paralysis (Bell’s palsy), carpal tunnel syndrome, and pain in isolated areas, like the front of the thigh, lower back, pelvic region, chest, stomach, inside the foot, and the shin.
According to Nancy Klobassa Davidson, R.N. and diabetic educator for the Mayo Clinic, “Pain relief (for focal neuropathy] can be among the most difficult aspects of managing the disorder. Often several treatments or a combination of treatments are tried before adequate relief can be found. For some people, the pain never goes away completely.”