Which hormone is involved in maintaining blood sugar levels as part of homeostasis?

• A. Calcitonin
• B. Insulin
• C. Adrenaline
• D. Melatonin

Answer: (B)

Blood sugar is kept within a narrow range by hormones that regulate glucose uptake and storage. Insulin, produced by the pancreas, is released when blood glucose rises after a meal. It tells body cells to take in glucose from the bloodstream and signals liver and muscle cells to convert excess glucose into glycogen for storage. This action lowers blood glucose back toward normal and maintains steady levels through a negative feedback loop.

Other hormones mentioned don’t regulate blood sugar in the steady, day-to-day way insulin does. Calcitonin controls calcium levels, not glucose. Melatonin influences sleep-wake cycles. Adrenaline can raise blood glucose quickly during stress by promoting glucose release from the liver, but it isn’t the ongoing regulator of blood sugar under normal conditions.