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This information was reviewed and approved by Bruce J. Lanser, MD, MPH (1/1/2014).

A diagnosis of diabetes can be made based on any of the following test results:

  • Hemoglobin A1C. An A1C of equal to or greater than 6.5%.

  • Fasting blood glucose test. A blood glucose level of 126 milligrams per deciliter (mg/dL) or more after an 8-hour fast.

  • A random (taken at any time of day) blood glucose level of 200 mg/dL or more, along with the presence of diabetes symptoms, on 2 or more occasions.

  • Oral glucose tolerance test. A blood glucose level of 200 mg/dL or more,  2 hours after drinking a beverage containing 75 grams of glucose dissolved in water.

Gestational diabetes is diagnosed based on blood glucose levels measured during the oral glucose tolerance test, though the cutoffs for diagnosis are lower because glucose levels are normally lower during pregnancy.

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