People with type 2 diabetes (non-insulin dependent diabetes) have a deficiency of a hormone called insulin. Insulin is produced by the pancreas and is the main hormone responsible for controlling sugar levels in the blood. It normally makes the cells of the body remove excess sugar from the blood. In type 2 diabetes insulin is produced inefficiently in response to surges of blood sugar, eg following a meal. The cells of the body also become resistant to the action of insulin that is produced, which means that blood sugar levels can become too high.

Glipizide works mainly by stimulating the cells in the pancreas that produce insulin. These cells are called beta cells. Glipizide causes the beta cells to produce more insulin. This helps to decrease the amount of sugar in the blood of people with type 2 diabetes.