From a pancreatic extract to a usable medicine
The breakthrough began with a biological puzzle: the pancreas was known to matter in diabetes, but its digestive juices made it difficult to isolate the substance that controlled blood sugar. In Toronto, physician Frederick Banting and medical student Charles Best worked with pancreases from animals to produce an extract containing insulin, the hormone that helps move sugar from the bloodstream into the body’s cells.
Their first preparations were crude. When the team tried one on Leonard Thompson, a 14-year-old with severe diabetes, in January 1922, it caused a serious reaction and produced little benefit. Biochemist James Collip then improved the extract’s purification. A second treatment, later that month, sharply reduced Thompson’s blood sugar and eased the immediate crisis.
Why insulin changed the outlook
In type 1 diabetes, the pancreas produces little or no insulin. Without it, sugar remains in the blood while the body struggles to use it for energy; over time, this can lead to dangerous illness and wasting. Before insulin, doctors sometimes restricted food severely to slow the rise in blood sugar. That could prolong life, but it could not replace the missing hormone.
Insulin made a different kind of care possible: patients could receive the substance their bodies lacked, rather than survive on ever-smaller meals. It was not a cure, and treatment required careful dosing. Too little insulin left blood sugar uncontrolled; too much could drive it dangerously low. But the change was immediate and profound: a diagnosis that had often meant a slow decline became manageable with regular treatment.
