cortisol is
Cortisol & Adrenal Function. Cortisol is a life sustaining adrenal hormone essential to the maintenance of homeostasis. Called âthe stress hormone,â cortisol influences, regulates or modulates many of the changes that occur in the body in response to stress including, but not limited to: 1  Blood sugar (glucose) levels. 2  Fat, protein and carbohydrate metabolism to maintain blood glucose (gluconeogenesis). 3  Immune responses.