Insulin

Insulin is a peptide hormone produced by the beta cells of the pancreatic islets of Langerhans that plays a central role in regulating blood glucose levels and energy metabolism. When you eat carbohydrates, they are broken down into glucose, which enters the bloodstream. Rising blood glucose stimulates the pancreas to release insulin, which acts like a key that unlocks cells throughout the body — allowing glucose to enter and be used for energy or stored for later use.

Beyond glucose regulation, insulin influences fat metabolism (promoting fat storage and inhibiting fat breakdown), protein synthesis (supporting muscle growth and repair), and cellular growth. It is sometimes called the body's 'storage hormone' because its primary effect is to facilitate the uptake and storage of nutrients after meals. When insulin levels are high (after eating), the body is in storage mode; when insulin levels are low (during fasting), the body shifts toward mobilizing stored energy.

Insulin dysfunction is at the core of diabetes mellitus. In type 1 diabetes, the immune system destroys the insulin-producing beta cells, requiring lifelong insulin injections. In type 2 diabetes — which accounts for about 90-95% of diabetes cases — the body's cells become resistant to insulin's effects (insulin resistance), requiring the pancreas to produce ever-increasing amounts until it eventually can't keep up. Understanding insulin is fundamental to understanding metabolic health, weight management, and the prevention and treatment of diabetes.

Insulin is the most important hormone in metabolic health. Fasting insulin levels and the HOMA-IR index (a measure of insulin resistance) are increasingly used to assess metabolic health even before blood glucose levels become abnormal. If your doctor has mentioned insulin resistance or prediabetes, it means your cells are requiring more insulin than normal to maintain glucose control — a condition that responds well to lifestyle interventions.

Strategies to improve insulin sensitivity include regular exercise (both aerobic and resistance training), weight management (particularly reducing visceral fat), a diet lower in refined carbohydrates and added sugars, adequate sleep, and stress reduction. These interventions can often prevent or delay progression from insulin resistance to type 2 diabetes.