the urine and the dog’s blood, both were overflowing with sugar. The dog had become severely diabetic. Some factor synthesized in the pancreas, they realized, must regulate blood sugar, and its dysfunction must cause diabetes. The sugar-regulating factor was later found to be a hormone, a protein secreted into the blood by those “islet cells” that Langerhans had identified. The hormone was called isletin, and then insulin—literally, “island protein.”
