What is insulin?

Insulin is a hormone made in the pancreas, an organ located behind the stomach. The pancreas contains clusters of cells called islets. Beta cells within the islets make insulin and release it into the blood.

Insulin plays a major role in metabolism—the way the body uses digested food for energy. The digestive tract breaks down carbohydrates—sugars and starches found in many foods—into glucose. Glucose is a form of sugar that enters the bloodstream. With the help of insulin, cells throughout the body absorb glucose and use it for energy.

Insulin’s Role in Blood Glucose Control

When blood glucose levels rise after a meal, the pancreas releases insulin into the blood. Insulin and glucose then travel in the blood to cells throughout the body.

Insulin helps muscle, fat, and liver cells absorb glucose from the bloodstream, lowering blood glucose levels.

Insulin stimulates the liver and muscle tissue to store excess glucose. The stored form of glucose is called glycogen.

Insulin also lowers blood glucose levels by reducing glucose production in the liver.

In a healthy person, these functions allow blood glucose and insulin levels to remain in the normal range.