The pancreas lies at the back of the abdomen and has two main functions:

to produce a juice that flows into the digestive system to help us digest food
to produce the hormone called insulin.

Insulin is the key hormone that controls the flow of glucose (sugar) in and out of the cells of the body.

Type 2 diabetes is caused by:

insufficient production of insulin in the pancreas
a resistance to the action of insulin in the body's cells - especially in muscle, fat and liver cells.

Type 2 diabetes is strongly associated with being overweight, but it's less clear what causes it, compared to the Type 1 disease.

In Type 2 diabetes, high levels of insulin circulate in the blood because the pancreas can still produce the hormone.

However, for reasons we don't understand, the effect of the insulin is impaired. This means it doesn't have its normal effect on the cells of the body. This is called insulin resistance.