Pancreas. Artwork showing the location of the pancreas in the body and detail of the tissue. At the centre of the circle is a cluster of cells, known as an islet of Langerhans, that secrete hormones into the blood. There are two types of cells, alpha cells (blue) and beta cells (orange), which both regulate blood sugar (glucose) levels. Beta cells secrete insulin, which converts glucose to its storage product glycogen, and so reduces blood sugar levels. Alpha cells secrete glucagon, which converts glycogen back to glucose and so increases blood sugar levels.