Today’s Google Doodle honors the 125th birthday of Sir Frederick Banting, the first person to use insulin to treat people with diabetes. That achievement garnered Banting a share of the 1923 Nobel Prize in Medicine. Most folks know that insulin is a lifesaving treatment, but fewer know how it works. I wouldn’t be writing about it if chemistry weren’t involved in the story, of course. So let’s dive in. Insulin is a natural protein that regulates energy consumption and blood sugar levels in the body. When a person develops Type 1 diabetes, the pancreas no longer produces enough insulin. Nowadays...