The amount of insulin, the fuel-regulating peptide hormone which is formed from proinsulin in the beta cells of the pancreatic islets and which promotes the storage of glucose and the uptake of amino acids, increases protein and lipid synthesis, and inhibits lipolysis and gluconeogenesis, in a specified sample of blood, the fluid that circulates through the heart, arteries, capillaries and veins carrying nutrients and oxygen to the body tissues and metabolites away from them.