Elevated pain threshold in patients with asymptomatic diabetic neuropathy: an intraepidermal electrical stimulation study

INTRODUCTION The loss of epidermal nerve fibers is regarded as an early pathological change in human diabetes. We investigated epidermal Aδ nerve fiber function by examining pain threshold by means of intraepidermal electrical stimulation (IES) in early diabetic neuropathy. METHODS We recruited 20 asymptomatic diabetic patients. Eighteen age-matched, healthy subjects served as controls. We placed the IES electrode onto the skin of the foot dorsum and delivered weak electrical stimulation. We defined pain threshold as the minimum electrical intensity at which a subject felt a pricking sensation. RESULTS The mean pain thresholds in the patient group were significantly higher (0.053 ± 0.036 mA; P