Glucose Tests Identify Sensory Polyneuropathy

Both the fasting plasma glucose level and the two-hour oral glucose tolerance test help to detect hyperglycemia (high blood sugar) and the consequences of disordered glucose metabolism.

Abnormal glucose metabolism, which occurs when the body has difficulty processing sugar (glucose) into energy, is twice as common among patients with chronic nerve dysfunction of unknown cause than among the general population and may be a risk factor for the condition, according to a study posted online in the June 12, 2006, edition of Archives of Neurology. When no underlying cause can be identified for painful sensory polyneuropathy despite extensive laboratory investigations, the neuropathy is referred to as chronic idiopathic axonal polyneuropathy (CIAP).

Charlene Hoffman-Snyder, M.S.N., of the Mayo Clinic (Scottsdale, AZ, USA), and colleagues identified 100 consecutive patients (60 women and 40 men) with CIAP. Patients underwent a complete neurologic evaluation and had a fasting plasma glucose test, which measures the levels of glucose in the blood after eight hours of not eating, and a two-hour oral glucose tolerance test, which determines how well the body processes glucose by drawing blood two hours after fasting patients ingest a dose of glucose.

According to the two-hour oral glucose tolerance test, 62 patients (62%) with neuropathy had abnormal fasting glucose metabolism, including 24 with undiagnosed diabetes. This compares with 33% of patients of similar ages in the general population with abnormal glucose metabolism, as previously estimated by the U.S. Centers for Disease Control and Prevention (CDC, Atlanta, GA, USA) in other published reports. The results of the current study suggest that abnormal glucose metabolism may be a risk factor for neuropathy.

"Conventional thinking among diabetologists is that diabetic polyneuropathies are the result of prolonged hyperglycemia,” the authors wrote. "Like previous studies, this investigation supports the hypothesis that distal axonal polyneuropathies may occur in much earlier stages of abnormal glucose metabolism than previously thought. Recent studies suggest that the neuropathy associated with impaired glucose tolerance may be milder than neuropathies traditionally associated with diabetes mellitus and may be the earliest detectable sign of abnormal glucose metabolism.”

The authors suggested that using the test may have clinical benefits since it would identify "opportunity for more aggressive management of the risks associated with hypoglycemia.”




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