The frequency of neuroaxonal dystrophy was determined in the superior mesenteric/celiac sympathetic ganglia in a streptozocin-treated rat model of diabetic autonomic neuropathy. Dystrophic axonopathy was increased 5- to 6-fold in 9-month untreated diabetics compared to age-matched controls. Pancreatic islet transplantation therapy or daily insulin administration prevented the development of dystrophic axonopathy. Transplantation of islets after 6 months of diabetes, a time at which dystrophic axonopathy is well developed, resulted in nearly complete resolution of the neuropathy within 3 months.