Normally, blood glucose levels increase after you eat a meal. When blood sugar rises, cells in the pancreas release insulin, causing the body to absorb glucose from the blood and lowering the blood sugar level to normal.
Through its various hormones, particularly glucagon and insulin, the pancreas maintains blood glucose levels within a very narrow range of 4–6 mM. This preservation is accomplished by the opposing and balanced actions of glucagon and insulin, referred to as glucose homeostasis.
Insulin helps the cells absorb glucose, reducing blood sugar and providing the cells with glucose for energy. When blood sugar levels are too low, the pancreas releases glucagon. Glucagon instructs the liver to release stored glucose, which causes blood sugar to rise.
Glucagon: Made by islet cells (alpha cells) in the pancreas, controls the production of glucose and another fuel, ketones, in the liver. Glucagon is released overnight and between meals and is important in maintaining the body's sugar and fuel balance.