The connection between neuropathy and IGM

Joshua Johnson, M.D.
General neurologist, peripheral nerve disorders
Providence Newberg Medical Center

Published May 2010

At least 20 million Americans have a neuropathy, and nearly 10 percent of Medicare patients have neuropathy as their primary or secondary diagnosis.

However, the laboratory workup of neuropathy can be unrevealing, with a diagnostic yield of 9 to 58 percent. The recent neuropathy literature suggests a connection between neuropathy and impaired glucose metabolism (IGM), a diagnosis based on an abnormal fasting glucose level, a two-hour glucose tolerance test or hemoglobin A1C.

Many patients with otherwise idiopathic neuropathy have IGM, with the frequency in the literature ranging from 48 to 62 percent.1-2 Most of these patients do not qualify as diabetic, and their abnormal glucose levels often remain untreated.

IGM seems to cause neuropathy by the same mechanisms as diabetes,3-7 and there is accumulating evidence that IGM should be treated aggressively in patients with neuropathy. The incidence of diabetes in patients with IGM is reduced by 58 percent with lifestyle intervention alone and by 31 percent with metformin.8

Similarly, patients with IGM and neuropathy decrease their neuropathic pain and objectively improve neuropathy when treated with lifestyle interventions or “intensive” glucose control.9-10 This literature should encourage aggressive glucose control in patients with impaired glucose metabolism of any severity.

Clinical articles by Joshua Johnson, M.D.