Prediabetes is a condition in which a person's blood sugar (glucose) level is above normal but below a level that indicates diabetes. Prediabetes has no symptoms and can only be diagnosed with a blood glucose test.

Prediabetes may be called impaired glucose tolerance or impaired fasting glucose, depending on the test used to diagnose it.

People who are age 45 or older and overweight are at risk for prediabetes. Also, people who are younger than 45 and overweight, and who have one or more other things that put them at risk for type 2 diabetes—such as a family history of diabetes; high blood pressure; high cholesterol; African-American, Asian-American, Hispanic, Native American, or Pacific Islander ethnicity; and/or a history of gestational diabetes (women)—are at risk for prediabetes.

Some people with prediabetes go on to develop type 2 diabetes later in life, and recent studies show that prediabetes increases the risk of heart disease. People with prediabetes may be able to prevent type 2 diabetes by losing weight, eating a healthy diet, and exercising regularly.