Which hormone regulates blood sugar levels?

Insulin is a hormone produced by the beta cells of the pancreas and plays a crucial role in regulating blood sugar levels. When food is consumed, especially carbohydrates, glucose levels in the bloodstream rise. Insulin facilitates the uptake of glucose by cells throughout the body, allowing them to use it for energy. Additionally, insulin encourages the liver to store excess glucose in the form of glycogen, which can be converted back to glucose when blood sugar levels drop. This regulation is essential for maintaining homeostasis, preventing conditions such as hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar).

In contrast, the other hormones listed serve different functions. Glucagon, also produced by the pancreas but by alpha cells, increases blood sugar levels by stimulating the liver to convert glycogen back into glucose when blood sugar is low. Cortisol, a stress hormone, affects metabolism and can increase blood sugar levels as part of the stress response but is not primarily responsible for day-to-day regulation. Adrenaline (epinephrine) also raises blood sugar levels during stress or 'fight or flight' responses but does so temporarily rather than maintaining overall blood sugar balance.