insulin
/ IN-suh-lin /
Insulin is the hormone that unlocks your cells so they can take in sugar from the blood and burn it for energy. Think of it as a doorman: after a meal, sugar floods into your bloodstream, your pancreas releases insulin, and the doorman waves that sugar inside the cells. Without him, the sugar piles up outside, stranded in the blood while the cells go hungry.
That pile-up is diabetes. In type 1, the pancreas makes little or no insulin at all; in the far more common type 2, the body still makes it but the cells stop listening, as if the doorman is shouting and no one answers. Either way, blood sugar climbs to dangerous levels while the body, starved of fuel, begins to break itself down.
A common mix-up: insulin does not 'cause' diabetes, and taking it is not a sign of failure or of eating too much sugar. It is replacement for something the body should make on its own. Before it could be given as medicine, a diagnosis of type 1 diabetes was a death sentence — children wasted away within months.
After breakfast, blood sugar rises → the pancreas releases insulin → cells open their doors → sugar moves in, and blood sugar settles back down.
Insulin is the signal that turns a post-meal sugar spike back into steady fuel.
The name comes from the Latin insula, 'island' — the hormone is made in tiny clusters of pancreatic cells called the islets of Langerhans. In 1921–22 in Toronto, Frederick Banting and Charles Best, working in J.J.R. Macleod's lab, first isolated it; the biochemist James Collip then purified the extract enough to treat a dying 14-year-old, Leonard Thompson, in January 1922 — an earlier, less pure injection had failed. Within a few years insulin became widely available and turned a fatal disease into a manageable one. The 1923 Nobel Prize went to Banting and Macleod, who shared their share with Best and Collip.