Fasting Insulin

Synonyms

Insulin sensitivity

Definition

Fasting insulin levels are primarily used to assess insulin sensitivity. Impaired insulin sensitivity precedes glucose intolerance in the development of type 2 diabetes. Elevated fasting insulin is a compensatory mechanism to prevent glucose intolerance and diabetes. Insulin resistance is defined as the impaired ability to promote peripheral glucose disposal and suppress hepatic glucose production.

The primary site of glucose disposal is skeletal muscle. The gold standard for measuring skeletal muscle insulin sensitivity is the hyperinsulinemic-euglycemic insulin clamp. This is an invasive and time-consuming test that involves infusion of a fixed rate of insulin and a variable rate of glucose to maintain normoglycemia; therefore, alternatives have been proposed. Calculations of fasting insulin and glucose can be used to measure insulin resistance. The most common are fasting glucose to insulin ratio, homeostasis model assessment of insulin...