Blood Glucose Regulation
The control of the amount of sugar (glucose) in the blood — the body’s circulating fuel supply. It is held in a narrow range: enough to fuel every cell (the brain especially depends on it) but not so much that it damages tissues.
The main controllers
Section titled “The main controllers”Two hormones from the pancreatic islets, acting in opposition:
- Insulin — released when glucose is high; moves glucose into cells and stores the surplus, lowering blood sugar.
- Glucagon — released when glucose is low; releases stored glucose from the liver, raising blood sugar.
Backup: the counter-regulatory hormones
Section titled “Backup: the counter-regulatory hormones”If glucose falls dangerously low, cortisol, growth hormone, and adrenaline reinforce glucagon — the body defends against low sugar more aggressively than against high sugar, because the brain fails quickly without fuel.
Key idea
Section titled “Key idea”Blood sugar is steadied by a push–pull between insulin and glucagon. When that balance fails, the result is diabetes. See the pancreatic / glucose axis.