What effect does cortisol have on blood sugar levels?

Cortisol has a well-documented role in glucose metabolism and is considered a key regulator in the body's response to stress. When cortisol levels rise, particularly in response to stress or fasting, it stimulates gluconeogenesis, which is the process of producing glucose from non-carbohydrate sources, primarily in the liver. This leads to an increase in blood sugar levels to provide immediate energy to cells and maintain metabolic function.

Additionally, cortisol opposes the action of insulin, the hormone responsible for lowering blood sugar levels. By decreasing insulin sensitivity, cortisol further contributes to elevated blood glucose levels during periods of stress. This metabolic response is critical to ensure that the body has sufficient energy available in times of physical demand or stress.

Thus, the response of cortisol to increase blood sugar levels is consistent with its role in the body's stress response, making this option the correct choice.