The discovery of insulin at the University of Toronto in 1921–22 was one of the most dramatic events in the history of the treatment of disease. Insulin’s impact was so sensational because of the incredible effect it had on diabetic patients. Those who watched the first starved, sometimes comatose, diabetics receive insulin and return to life saw one of the genuine miracles of modern medicine. They were present at the closest approach to the resurrection of the body that our secular society can achieve, and at the discovery of what has become the elixir of life for millions of human beings around the world. This book is an attempt to re- create the discovery of insulin as accurately and fully as can be done in a single volume. It draws on a vast body of primary source material never before available to researchers. It reflects no point of view other than a professional historian’s obligation to be as objective and fair as possible. It is written to be read by anyone from a scientist to a high school student, and especially by those in between. Many readers will begin this book believing they have a reasonably clear understanding of the discovery of insulin. It is a story told in several books, in textbook accounts, in films, tapes and television programs. In broad outline, the conventional history is something like this: By the early years of the twentieth century it was understood that the disease named diabetes mellitus involves the body’s inability to metabolize or utilize its food, especially carbohydrates. It was also understood that the pancreas holds the key to carbohydrate metabolism.