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How is prediabetes diagnosed?

Doctors can use either the fasting plasma glucose test (FPG) or the oral glucose tolerance test (OGTT) to detect prediabetes. Both require a person to fast overnight. In the FPG test, a person's blood glucose is measured first thing in the morning before eating. In the OGTT, a person's blood glucose is checked after fasting and again 2 hours after drinking a glucose-rich drink.
Dana Artinyan
Nutrition & Dietetics
Prediabetes is diagnosed by a fasting blood sugar of 100 to 125 mg/dL.
Your doctor can look at a couple of things to diagnose prediabetes. The main thing usually used to diagnose this is a blood draw looking at your fasting blood sugar levels (typically after at least 8 hours without food or drinks other than water); between 100-125 mg/dl is considered prediabetes, and anything above this on two occasions is considered diabetes. Sometimes a hemoglobin A1C is also checked, which gives your average blood sugar level over a 3-month period. If this is between 5.7% and 6.4%, the person is also considered to have prediabetes.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.