Fasting insulinHOMA-IR

Fasting insulin is the amount of the hormone insulin circulating in your blood after an overnight fast. Insulin is what moves sugar out of the blood and into cells, so the level shows how hard the pancreas is working to keep glucose normal.

It matters because a high fasting insulin — especially alongside still-normal glucose — is a classic early sign of insulin resistance, often flagging a metabolic problem years before glucose itself starts to rise. Combined with glucose it gives the HOMA-IR estimate of insulin resistance.

In practice, fasting insulin adds depth to glucose and HbA1c: someone can keep 'normal' glucose only by pumping out lots of insulin, which fasting insulin exposes. It responds to the same levers — activity, muscle, sleep and avoiding chronic surplus.