How Does Insulin Control Blood Sugar?

When you eat carbohydrates, they are broken down into glucose that enters the bloodstream. Beta cells in the pancreas's islets of Langerhans sense rising glucose and release insulin. Insulin acts like a key, signalling muscle and fat cells to move glucose transporters to their surface so sugar can enter. It also tells the liver to store glucose as glycogen and to stop making new glucose. When blood sugar falls, another pancreatic hormone, glucagon, does the opposite, releasing stored glucose.