Insulin

The hormone your pancreas releases to move glucose out of the blood and into cells.

Insulin climbs for years while glucose still looks normal, so it is often where insulin resistance shows up first.

Only a fasting value is interpretable, and the assay differs enough between labs that values are hard to compare across providers. Read it with fasting glucose from the same draw -- neither number means much alone.

Worth discussing a fasting value that climbs across several tests even while glucose holds steady.