Insulin is the hormone produced in the pancreas by the islets of Langerhans, which regulates the amount of glucose in the blood. Insulin helps to keep the blood sugar level from getting too high or too low. The lack of insulin causes a form of Diabetes. Insulin is a peptide hormone, produced by beta cells in the pancreas, and is central to regulating carbohydrate and fat metabolism in the body. It causes cells in the skeletal muscles, and fat tissue to absorb glucose from the blood.