(HealthDay News) – Early axonal dysfunction may be detected prior to the development of clinical symptoms of diabetic neuropathy.

Jia-Ying Sung, MD, of Wan Fang Hospital in Taipei, Taiwan, and colleagues conducted a study involving 56 patients with type 2 diabetes without neuropathy and 52 patients with diabetes and neuropathy to evaluate (using nerve excitability techniques) whether diabetic neuropathy is associated with changes in peripheral axonal function. Patients with neuropathy were further categorized according to severity into grade 0, 1, and 2/3.

Compared with age-matched controls, the researchers found that patients with type 2 diabetes but no clinical symptoms of neuropathy displayed significantly increased threshold, prolonged latency, and changes in excitability parameters. Significant alteration was seen in recovery cycle parameters and depolarizing threshold electrotonus in patients with neuropathy. For patients without neuropathy, glycated hemoglobin levels correlated significantly with latency and subexcitability, while superexcitability correlated with the estimated glomerular filtration rate in those with neuropathy. As the severity of neuropathy increased, nerve excitability parameters became more abnormal.

“These results suggest a spectrum of excitability abnormalities in patients with diabetes and that early axonal dysfunction may be detected prior to the development of neuropathy,” the authors write. “As progressive changes in excitability parameters correlated to neuropathy severity, excitability testing may provide a biomarker of the early development and severity of diabetic neuropathy, providing insights into the pathophysiological mechanisms producing axonal dysfunction.”

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