Insulin is a peptide hormone produced by the beta cells of the pancreatic islets. It acts as a key regulator of blood glucose, promoting uptake and storage of glucose into liver, muscle, and fat tissues, and it also influences fat and protein metabolism. Here’s a concise overview of what insulin is and what it does. What insulin is

• A hormone composed of 51 amino acids in humans, synthesized in the pancreas from the INS gene, and stored in secretory vesicles in beta cells until released into the bloodstream.

• Structurally, insulin is formed as its precursor (preproinsulin), which is processed to proinsulin and then cleaved to mature insulin and C-peptide before secretion. The mature hormone consists of two chains (A and B) linked by disulfide bonds.

What insulin does

• Regulates blood glucose by facilitating cellular glucose uptake, especially in skeletal muscle and adipose tissue, and signals the liver to store glucose as glycogen. This helps lower post-meal blood glucose levels.

• Influences other metabolic pathways, including promoting protein synthesis, lipogenesis, and glycogen formation, while inhibiting hepatic glucose production when circulating glucose is high.

• Its release is stimulated by rising blood glucose and certain amino acids, and modulated by neural input and hormones; cortisol and other counterregulatory hormones can antagonize insulin’s actions during stress.

Why insulin matters clinically

• Defects in insulin production or action underpin diabetes mellitus: type 1 involves little or no insulin production, while type 2 involves insulin resistance with impaired signaling and, over time, reduced insulin secretion. Management often requires exogenous insulin or medications that enhance insulin action.

• Insulin therapy aims to mimic physiological insulin patterns to maintain blood glucose within target ranges and reduce complications of diabetes. Different forms exist (rapid-acting, short-acting, intermediate-acting, long-acting) with distinct onset and duration profiles.

If you’d like, I can tailor this to a specific question (e.g., molecular structure, how insulin signaling works at the cellular level, or clinical management in diabetes) and provide more focused details.