Insulin is a vital hormone in the human body, primarily produced by the beta cells of the pancreas. Its main function is to regulate blood sugar levels by facilitating the uptake of glucose into cells for energy production or storage. Insulin plays a crucial role in metabolism, promoting the synthesis of glycogen, fat, and protein. It also inhibits the breakdown of stored glucose, fat, and protein. Insulin secretion is tightly regulated in response to fluctuating blood glucose levels, with increased secretion after meals and decreased secretion during fasting. Insulin deficiency or insensitivity can lead to hyperglycemia, a hallmark of diabetes mellitus. Proper insulin function is essential for maintaining glucose homeostasis and overall metabolic health in the human body.