Which hormone is primarily responsible for the management of blood glucose levels?

Insulin plays a critical role in the regulation of blood glucose levels. It is produced by the beta cells of the pancreas in response to elevated blood glucose levels, typically after meals. Insulin facilitates the uptake of glucose into tissues, particularly in muscle and adipose (fat) tissues, thereby lowering blood glucose levels. It promotes the conversion of glucose into glycogen for storage in the liver and muscle cells, and enhances fat storage while inhibiting the breakdown of fat and protein.

In contrast, hormones like cortisol, epinephrine, and thyroid hormone have different roles in the body's metabolism. Cortisol is known to increase blood glucose levels through gluconeogenesis during times of stress or fasting. Epinephrine, or adrenaline, also raises blood glucose levels during 'fight or flight' situations by promoting glycogen breakdown and inhibiting insulin release. Thyroid hormones primarily regulate metabolism and energy expenditure but do not have the direct role that insulin does in managing blood glucose levels. Thus, insulin is unequivocally the key hormone responsible for maintaining glucose homeostasis in the body.