Abnormal glucose metabolism common in chronic nerve disorder

Friday, October 13, 2006

SCOTTSDALE, Ariz. - 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.

Some older adults can experience a nerve disorder known as neuropathy, which can be characterized by symptoms of "burning feet" and other unpleasant sensations in the lower leg. Diabetes, genetic disease, exposure to toxins and primary amyloidosis, a condition in which extra protein accumulates in the body tissues, can all cause neuropathy, but many cases do not have a clear identifiable cause. When laboratory tests cannot determine the cause, the condition is known as chronic idiopathic axonal polyneuropathy (CIAP), or chronic nerve disorder.

Researchers at Mayo Clinic studied 100 patients with chronic idiopathic axonal polyneuropathy. Patients underwent a complete neurological evaluation, a fasting plasma glucose test (to measure the levels of glucose in the blood after not eating for eight hours), and a two-hour oral glucose tolerance test, which determines how well the body processes glucose by drawing blood two hours after fasting patients swallow a sugar solution (glucose).

"The popular belief is that patients need to have an established diagnosis of diabetes for many years before they develop symptoms associated with chronic idiopathic axonal polyneuropathy," said lead investigator Charlene Hoffman-Snyder, N.P., Mayo Clinic in Arizona. "When no known cause is found to explain chronic idiopathic axonal polyneuropathy, further investigation for impaired glucose tolerance is needed. We suggest using the two-hour oral glucose tolerance test."

Thirty-nine patients had abnormal fasting plasma glucose metabolism under the 2003 revised American Diabetes Association criteria, whereas 62 patients had abnormal fasting glucose metabolism using the two-hour glucose tolerance test, the researchers reported in the August issue of the Archives of Neuropathy. The results of the current study suggest that abnormal glucose metabolism may be a risk factor for neuropathy.

"We hope the study helps clinicians identify patients at high risk for impaired glucose metabolism and diabetes at an early point in these disorders to allow for reduction of their risk for long-term complications," said Hoffman-Snyder.

This study adds to emerging evidence that abnormal glucose metabolism may be a risk factor for CIAP. Further studies are being considered including collection of data from simultaneous normal control subjects and interventional studies to treat CIAP before diabetes mellitus develops.

Mayo Clinic is the first and largest integrated, not-for-profit group practice in the world. As a leading academic medical center in the Southwest, Mayo Clinic focuses on providing specialty and surgical care in more than 65 disciplines at its outpatient facility in north Scottsdale and at Mayo Clinic Hospital. The 208-licensed bed hospital is located at 56th Street and Mayo Boulevard (north of Bell Road) in northeast Phoenix, and provides inpatient care to support the medical and surgical specialties of the clinic, which is located at 134th Street and Shea Boulevard in Scottsdale.

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