Pancreas - Endocrine Function

Pancreas is formed by islets of Langerhans, which are clusters of specials cells.
There are two type of  these special cells beta cells and alpha cells.
Beta cells secrete Insulin, which takes action when the blood glucose level rises. Insulin makes the target cells more permeable to glucose and stimulate them to convert glucose into glycogen and store it.
Alpha cells secrete Glucagon. Stimulates the liver to produce glycogen back to glucose. It is used when the level of sugar is low.

Disorders 

Diabetes: There are two types of diabetes, type 1 (juvenile) which is the attack to the beta cells from the immune system, and type 2 (adult -onset) which can be the malfunction of the beta cells, or the body is not responded well to the insulin as it should.
Hyperglycemia: Condition generated when there is high level of blood sugar in the body.