胰岛（兰格尔翰斯岛，德语: Langerhans-Inseln 英语: Islets of Langerhans）在1869年由德国病理学家保罗·兰格尔翰斯（Paul Langerhans)所发现。胰岛是胰脏里的岛状细胞团，由一群分泌激素的细胞所组成。胰岛的直径是50-500μm之间，每个胰岛含有约1000个细胞。

胰岛内有5种分泌激素的细胞：

The pancreatic islets or islets of Langerhans are the regions of the pancreas that contain its endocrine (i.e., hormone-producing) cells. Discovered in 1869 by German pathological anatomist Paul Langerhans. New studies show that the pancreatic islets constitute approximately 4.5% of the pancreas volume and receive 10-15% of its blood flow. The islets of Langerhans are arranged in density routes throughout the healthy human pancreas.