A 53 yr old woman requiring more than 300 units of NPH insulin per day to control persistent hyperglycemia was found to have a large glucagon secreting islet cell carcinoma of the pancreas. The angiographic findings were more consistent with those seen in a cystadenoma or cystadenocarcinoma of the pancreas. The striking clinical history and radioimmunoassay studies limited the diagnosis to a functioning islet cell tumor, presumably a glucagonoma.
