What is the Origin of Insulin Sensitivity Index?

The ISI concept originates from quantitative glucose tolerance testing and the need to precisely assess the degree of insulin resistance in clinical endocrinology. It formalizes the relationship between insulin action and glucose homeostasis, providing a standardized metric for metabolic assessment. This index helps delineate pre-diabetic states accurately.

What is the Mechanism of Insulin Sensitivity Index?

The index functions by mathematically relating the concentration of the signaling molecule (insulin) to the magnitude of the resulting biological effect (glucose uptake by muscle and fat cells). High fidelity in this signaling pathway means cellular GLUT4 transporters are readily mobilized upon insulin binding to the receptor. Improvements in ISI often correlate with enhanced mitochondrial function and reduced intramyocellular lipid accumulation.

Insulin Sensitivity Index

Meaning

Insulin Sensitivity Index (ISI) is a quantitative measure derived from clinical data, often incorporating fasting glucose and insulin levels or dynamic testing, that reflects the efficiency with which peripheral tissues respond to circulating insulin. A high index indicates that lower insulin concentrations are required to achieve glucose disposal, signifying superior metabolic health. Conversely, a low ISI is a strong predictor of impending metabolic syndrome.