What was Banting's central theory about diabetes?
My central idea was that diabetes was caused by a lack of a specific internal secretion from the pancreas, not by overeating or a mysterious imbalance. Others had tried to isolate this substance—what we now call insulin—but failed because the digestive enzymes in the pancreas destroyed it. I theorized that if we tied off the pancreatic ducts in dogs, the enzyme-producing cells would degenerate, leaving the islet cells intact. Then we could extract the secretion from those islets. That was the key: we had to be ruthless with our own ideas and test them directly. We didn't have time for fancy theories; people were dying. So we just tried it. The experiment worked, and the extract lowered blood sugar. Nature doesn't lie—only our interpretations do.
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