Excess of which hormone causes hyperglycemia by promoting gluconeogenesis and glycogenolysis?

The hormone that is responsible for causing hyperglycemia by promoting gluconeogenesis and glycogenolysis is corticosteroid. Corticosteroids, particularly cortisol, increase blood glucose levels during stressful situations by stimulating these metabolic pathways.

Gluconeogenesis is the process of generating glucose from non-carbohydrate sources, while glycogenolysis is the breakdown of glycogen to glucose. Corticosteroids enhance these processes, leading to increased glucose availability, which may result in hyperglycemia.

In contrast, insulin's primary role is to lower blood glucose levels by facilitating cellular uptake of glucose and inhibiting gluconeogenesis and glycogenolysis. Growth hormone can have a counter-regulatory effect on insulin and may promote hyperglycemia but is not primarily responsible for those processes. Thyroid hormones are involved in basal metabolic rate and energy expenditure but do not directly promote hyperglycemia through gluconeogenesis and glycogenolysis.