Insulinoma after streptozotocin therapy for metastatic gastrinoma: natural history or iatrogenic complication? Islet cell carcinoma frequently produces more than one chemical product, although its clinical expression is usually restricted to a single hormone. We describe an unusual patient who presented with full-blown metastasizing gastrinoma. He was treated with cimetidine for five years and then streptozotocin therapy, which resulted in a regression in hepatomegaly and a fall in serum gastrin levels. Following one year's therapy with streptozotocin, he was admitted in hyperinsulinemic hypoglycemic stupor. This appears to be the first reported case of a "shift" from clinical gastrinoma to insulinoma possibly related to prolonged streptozotocin therapy. 