The structure in the human body that produces insulin is the pancreas. Located behind the stomach, the pancreas plays a crucial role in digestion and blood sugar regulation. It contains clusters of cells known as the islets of Langerhans, which produce insulin and other hormones. Insulin is vital for controlling blood glucose levels, allowing cells to absorb sugar for energy. Malfunction of insulin production can lead to diabetes mellitus, a condition affecting millions worldwide. The pancreas, therefore, is essential not just for digestion but for maintaining metabolic balance in the body.