Fasting Blood Sugar: normal range & what your result means

Fasting blood glucose is measured after 8 hours without food. It is a first-line test for diabetes and prediabetes.

Typical adult reference range

Measure	Range
Normal	70–99 mg/dL
Prediabetes	100–125 mg/dL
Diabetes	≥ 126 mg/dL (confirmed)

What a HIGH result can mean

100–125 mg/dL = prediabetes; ≥126 (on two tests) = diabetes
Very high readings with symptoms need prompt care

What a LOW result can mean

Below ~70 mg/dL is low (hypoglycaemia): shakiness, sweating, confusion — treat with fast sugar

Ranges vary by lab. Reference ranges are TYPICAL ADULT values and vary by laboratory, age, sex, pregnancy and the method used. Always read your result against the range printed on YOUR report, and let your doctor interpret it alongside your history.

Frequently asked questions

How long should I fast before this test?

Usually 8–12 hours of no food or drink except water. Take it in the morning, and check with your doctor about any medicines beforehand.

What level means diabetes?

A fasting glucose of 126 mg/dL or above, confirmed on a second test, indicates diabetes; 100–125 is prediabetes. HbA1c is often checked alongside.

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MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.