Pioglitazone is used with a diet and exercise program and sometimes with other medications, to treat type 2 diabetes (condition in which the body does not use insulin normally and therefore cannot control the amount of sugar in the blood). Pioglitazone is in a class of medications called thiazolidinediones. It works by increasing the body's sensitivity to insulin, a natural substance that helps control blood sugar levels. Pioglitazone is not used to treat type 1 diabetes (condition in which the body does not produce insulin and, therefore, cannot control the amount of sugar in the blood) or diabetic ketoacidosis (a serious condition that may develop if high blood sugar is not treated).