In the Islets of Langerhan ( human anatomy), which cell secretes insulin?

The Islets of Langerhans (or the pancreatic islets) are the regions of the pancreas that contain its endocrine (hormone-producing) cells, discovered in 1869 by German pathological anatomist Paul Langerhans (25th July 1847-20th July 1888). The pancreatic islets constitute 1 to 2% of the pancreas volume and receive 10-15% of its blood flow. There are about 3 millions islets distributed with each measures an average of about 0.1mm (109 micro m) in diameter.

The 'beta cells' are a type of cells found in pancreatic islets that secrete 'insulin' (a peptide hormone). In patients with type-1 or type-2 diabetes, beta-cells mass functions are diminished leading to insulin secretion. The 'beta cells' are selectively destroyed by an auto-immune process in type-1 diabetes. The clinicians and researchers are actively pursuing islet transplantation as a means of restoring physiological 'beta cell' function. The islet transplantation emerged as a viable option for the treatment of 'insulin' requiring diabetes in the early 1970s with steady progress over last three decades.