Painful sensory polyneuropathy associated with impaired glucose tolerance

We examined records of 121 patients coded as idiopathic polyneuropathy, extracting neuropathy symptoms, electromyographic data, and diagnostic blood work. Of 89 patients screened for glucose handling, 28 demonstrated frank diabetes mellitus. Of the remaining 61 patients, 15 (25%) had impaired glucose tolerance (IGT) by American Diabetes Association criteria (serum glucose 140--200 mg/dl 2 h after a 75-g glucose load). Excluding those with diabetes mellitus, 35% of patients with neuropathic pain had IGT, more than twice the prevalence found in large, unselected population studies. No other common etiology of polyneuropathy was identified. Two-hour oral glucose tolerance test results were often abnormal, whereas fasting glucose or hemoglobin A1c was normal. Bias due to referral pattern, body weight, or genetics might affect the comparison of our polyneuropathy cohort with a broader, population-based control. However, our results corroborate an association between IGT and painful sensory polyneuropathy and link these patients syndromically to the typical painful polyneuropathy of diabetes mellitus.