Insulin is a substance made by the pancreas to help the body store energy from food. People with type 2 diabetes mellitus make plenty of insulin, but their bodies cannot use it normally, resulting in high blood sugar levels. Some people do not have type 2 diabetes but have “insulin resistance.” People with insulin resistance do not have the high blood sugar levels that occur in people with type 2 diabetes, but their bodies must produce large amounts of insulin to keep sugar levels normal. Insulin resistance can progress to type 2 diabetes. People with type 2 diabetes have a high risk for heart disease. Some studies suggest that insulin resistance is also associated with heart disease but could not determine whether the higher rates of heart diseases in people with insulin resistance were due to the insulin resistance or to other risk factors for heart disease, such as high blood pressure, smoking, or abnormal cholesterol levels.