What is fasting insulin and why does it matter?

Full answer

Fasting insulin is one of the earliest sensitive markers of insulin resistance. Because the pancreas compensates for declining cellular insulin sensitivity by secreting more insulin, fasting insulin frequently rises years — sometimes a decade — before fasting glucose or hemoglobin A1c cross diagnostic thresholds. A fasting insulin in the high single digits or above, especially paired with even mildly elevated fasting glucose, is a meaningful early signal. It is interpreted with fasting glucose and the HOMA-IR derivation (the product of the two, scaled), which standardizes the read. Provider-reviewed wellness uses this trio to identify metabolic drift early enough that lifestyle, body-composition, and — where indicated — GLP-1 pathways can change the trajectory before frank diabetes develops.

Educational. Not a substitute for individualized provider review.