Final answer:
Insulin is the hormone released by the islets of Langerhans to regulate sugar levels in the body.
Step-by-step explanation:
The hormone released by the islets of Langerhans to regulate sugar levels in the body is insulin.
Insulin is produced by the beta cells in the pancreatic islets. It helps lower blood glucose levels by promoting the uptake of glucose by the body's cells and facilitating glycogen synthesis in skeletal muscles and the liver.
Therefore, insulin plays a crucial role in maintaining blood glucose homeostasis and preventing high blood glucose levels.