Insulin is produced primarily in the pancreas, specifically by the beta cells located in the islets of Langerhans within the pancreas
. These beta cells synthesize and secrete insulin in response to blood glucose levels, helping regulate metabolism by promoting glucose uptake in tissues such as the liver, fat, and muscles
. While the pancreas is the main source, some studies have found insulin production in other tissues, such as the thymus, liver, adipose tissue, spleen, and bone marrow, especially under diabetic conditions, but this extrapancreatic insulin production is not the primary physiological source
. In summary, insulin is produced in the beta cells of the pancreatic islets of Langerhans, an organ located behind the stomach
