The Four Major Hormones That Increase Blood Sugar
The four major counterregulatory hormones that increase blood glucose are glucagon, cortisol, growth hormone, and epinephrine (adrenaline). These hormones antagonize insulin action and work together to prevent hypoglycemia and maintain glucose homeostasis 1, 2.
Mechanism of Action
These hormones are triggered in a hierarchical fashion as blood glucose drops:
Glucagon (first responder): Increases hepatic glycogenolysis and gluconeogenesis, directly raising blood glucose by mobilizing liver glucose stores 3
Epinephrine/Adrenaline (most potent acute effect): Exerts the strongest diabetogenic action during short-term administration, causing marked increases in blood glucose and tripling insulin requirements. It stimulates hepatic glucose production and provides substrates for gluconeogenesis through glycolysis and lipolysis 4
Growth hormone (delayed but sustained): The second strongest diabetogenic hormone after epinephrine. It decreases glucose oxidation, suppresses muscle glucose uptake, and redistributes glucose into non-oxidative pathways. Effects become apparent in states of GH excess 4, 5
Cortisol (long-term regulator): Decreases tissue insulin sensitivity and increases hepatic glucose production. Its diabetogenic effects are more subtle acutely but significant with chronic elevation [4, @23@]
Clinical Significance
In pathological states, excess amounts of these hormones cause diabetes or worsen existing diabetes:
- Acromegaly (excess growth hormone)
- Cushing's syndrome (excess cortisol)
- Glucagonoma (excess glucagon)
- Pheochromocytoma (excess epinephrine) 1, 2
These conditions typically cause hyperglycemia in individuals with preexisting insulin secretion defects, and glucose levels generally normalize when the hormone excess resolves 1, 2.
Counterregulatory Response Hierarchy
When blood glucose falls below 0.65-0.70 g/L (3.6-3.9 mmol/L), the counterregulatory cascade activates in this order 3:
- First: Glucagon secretion (increases glycogenolysis and gluconeogenesis)
- Then: Epinephrine release (similar hepatic effects plus substrate mobilization)
- After >1 hour: Growth hormone and cortisol (sustained anti-hypoglycemic effects through decreased insulin sensitivity and increased hepatic glucose production)
Important caveat: While these hormones are considered "diabetogenic," their dysfunction is secondary to insulin deficiency in diabetes mellitus, not the primary cause 6. They represent inappropriate compensatory responses that may aggravate the diabetic syndrome but do not cause diabetes itself.