Insulin Sensitivity

Insulin sensitivity refers to how efficiently target cells, primarily in skeletal muscle, adipose tissue, and the liver, respond to the hormone insulin by activating glucose transporters (mainly GLUT4) and downstream metabolic pathways including glycogen synthesis, lipogenesis, and protein synthesis. High insulin sensitivity means cells require less insulin to achieve adequate glucose uptake, while reduced sensitivity (insulin resistance) necessitates greater insulin output from pancreatic beta cells and is a hallmark of metabolic syndrome and type 2 diabetes. Factors that improve insulin sensitivity include exercise, caloric restriction, adequate sleep, and certain pharmacological agents. Tirzepatide, a dual GIP/GLP-1 receptor agonist, has demonstrated significant improvements in insulin sensitivity in clinical trials through mechanisms including enhanced incretin signalling, reduced hepatic lipid content, and improved adipose tissue function. Peptides that support lean body mass and metabolic rate, such as growth hormone secretagogues, may also indirectly improve insulin sensitivity by modulating body composition.