We report a case of acute, painful polyneuropathy in a boy with newly diagnosed type 1 diabetes mellitus associated with a precipitous drop in hemoglobin A1c. After initiation of insulin, the patient's hemoglobin A1c dropped from 14.1 to 7.6%, and he developed severe pain in his feet, which prevented him from walking. Nerve conduction studies were consistent with mild to moderate sensorimotor peripheral neuropathy. Initially, he required opiate analgesics for pain control. Three months after presentation, the patient showed dramatic improvement and regained his ability to walk. Although not well described in the pediatric literature, this case represents insulin neuritis, one of the few diabetic neuropathies that has a favorable outcome.