What Is a Fasting Blood Glucose Level?

What Is a Fasting Blood Glucose Level?

A fasting blood glucose (also known as sugar) level is the measurement of glucose in the blood after a person has been fasting, or not eating any food or beverage (besides water) for at least eight hours.1

If a person has their fasting blood glucose checked by their healthcare provider, this test is usually performed after an overnight and prior to eating. It may be in the morning or early part of the day. For people who check their glucose levels, either with a blood glucose meter or with a continuous glucose monitor, a fasting glucose check is typically done when they wake from sleeping.   

A normal fasting blood glucose level is below 100 mg/dL. Individuals whose blood glucose is at or above 100mg/dL but under 126 mg/dL can be diagnosed with prediabetes.2 People whose blood glucose is at or above 126 mg/dL can be diagnosed with diabetes.2 Keep in mind that several caveats apply to the diagnosis of prediabetes and diabetes. Anyone who discovers their fasting glucose level is high should discuss the result with their healthcare provider and come up with a plan to address this.   

Reference:
1: ADA. Understanding A1c, Diagnosis. https://www.diabetes.org/a1c/diagnosis. Accessed July 5, 2021.
2: ADA. 2. Classification and diagnosis of diabetes: Standards of medical care in diabetes – 2021. Diabetes Care.2021;44(Supp1):S15-33).

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