Glucose is a simple sugar that forms the molecular foundation of large carbohydrate molecules. The carbohydrates in grains, for example, contain hundreds or thousands of glucose units chained together. The digestive system breaks down carbohydrate from your diet and absorbs the sugar into your bloodstream. This is the provenance of the term "blood sugar." The cells in the human body use glucose as an important source of energy. However, high levels of blood glucose are dangerous and can lead to nerve damage.
Blood Sugar
Hyperglycemia is a condition characterized by excess glucose circulating in the blood. In the short term, hyperglycemia can produce symptoms such as fatigue and blurred vision. Chronic hyperglycemia, however, can also damage tissue and cause various injuries to the small vessels that supply blood to the nerves.
Diabetes
Due to the similarity of their origins, diabetes and glucose-related nerve damage are closely associated conditions. Diabetes is a group of metabolic diseases in which the human body fails to produce enough insulin or the cells do not respond to the insulin that is present. Insulin is an essential regulatory hormone that causes cells to take up glucose from the blood and use it as energy. Without the ability to respond to insulin, glucose can rise to dangerous levels, exacerbating nerve damage. Diabetic neuropathy is the name for the family of nerve disorders related to diabetes. Approximately 60 to 70 percent of diabetics have some form of neuropathy, though neurovascular and autoimmune disorders are also to blame.
Glucose Tolerance
A group of researchers from the University of Utah in 2001 published a study in the journal "Diabetes Care" that suggests subjects with impaired glucose tolerance are at a greater risk for nerve damage. The researchers measured this tolerance by using the American Diabetes Association diagnostic criteria; during the test, the subject took carbohydrates to see how fast the glucose cleared from the blood. After 2 hours, people with impaired glucose tolerance still had abnormally high blood glucose levels somewhere between 140 and 200 mg/dL --- or milligrams of glucose per deciliter of blood. Levels below 140 mg/dL are generally normal.
Types
There are several different types of diabetic neuropathy. Peripheral neuropathy is the most common form; it affects the legs, arms, hands and feet. Autonomic neuropathy causes symptoms in the digestive system, bowels, bladder and sexual functions, as well as the nerves that affect the heart, lungs and eyes. Proximal neuropathy causes pain in the thighs, hips or buttocks. Focal neuropathy affects one nerve or a group of nerves anywhere in the body.
Symptoms
Some people with diabetic neuropathy have no symptoms. Most, however, will experience pain, tingling, weakness, numbness and loss of feeling in the extremities. Other symptoms, depending upon the type of neuropathy, can include gastrointestinal problems, dizziness, faintness, difficulty urinating, sexual problems and the wasting away of the muscles in the hands and feet.
