The Facts
Hypoglycemia occurs when the level of glucose (sugar) in the blood is too low. Normally, your body keeps your blood glucose within a concentration range of 70 mg/dL to 110 mg/dL (3.8 mmol/L to 6.1 mmol/L). In order to do this, the body has mechanisms that involve the hormone insulin, which is made by the pancreas.
Insulin lowers the amount of glucose in your blood by signaling the cells in the body to take up glucose as fuel. When blood sugar levels rise, the pancreas responds by releasing insulin to promote glucose disposal.
Your body uses glucose as its main fuel. The brain requires a constant supply of blood glucose and will signal the adrenal glands to release a hormone called adrenaline whenever blood glucose levels are low. The adrenaline then signals the liver to convert the carbohydrates it stores (from the foods we eat) into glucose and release it into to bloodstream. If this mechanism doesn't work properly, the blood glucose remains too low and the brain won't be able to function normally.