FBS Test (Fasting Blood Sugar)

FBS Test: quick answers

FBS Test full form

Fasting Blood Sugar

FBS Test price

₹97, home sample collection

Normal range (adults)

Normal: 70–99 mg/dL; Prediabetes (impaired fasting glucose): 100–125 mg/dL more

Done for

Screening for diabetes and prediabetes; Symptoms such as excess thirst, frequent urination or weight loss; Monitoring people already treated for diabetes

Fasting

Required (8-12 hours)

Report

Within 2 hours

What is the FBS Test?

The FBS test measures the glucose (sugar) in your blood after at least 8 hours without food. It is one of the standard tests used to screen for diabetes and prediabetes, and to check how well diabetes is controlled.

FBS Test normal range

These are the American Diabetes Association cut-offs. WHO uses 110–125 mg/dL for impaired fasting glucose. One high value is usually repeated, or paired with HbA1c, before diabetes is confirmed.

Ranges differ between laboratories and methods. The reference range printed on your own report is the one to read your result against.

What your FBS Test result means

High

A value of 100–125 mg/dL suggests prediabetes; 126 mg/dL or more on two occasions meets the criterion for diabetes. Illness, stress, steroids and not fasting long enough can also raise it.

Low

Below 70 mg/dL is low blood sugar. It is most often seen in people taking insulin or some diabetes tablets, and needs a doctor's review if it happens without them.

One result is not a diagnosis. A doctor reads it with your symptoms, history, medicines and other tests.

FBS Test levels: what does my number mean?

Fasting sugar 70 to 99 mg/dL

Normal fasting blood sugar after at least 8 hours without food.

Fasting sugar 100 to 125 mg/dL

Impaired fasting glucose, also called prediabetes. Doctors often add an HbA1c to see the average over the last few months. Often checked next: HbA1c Test.

Fasting sugar 126 mg/dL or higher

126 mg/dL or higher on two separate tests is the cut-off for diabetes. A single reading is usually confirmed with a repeat fasting test or an HbA1c. Often checked next: HbA1c Test.

Fasting sugar below 70 mg/dL

Low blood sugar (hypoglycaemia). In someone on diabetes medicine it usually means the dose or meals need adjusting; shakiness, sweating or confusion with a low reading needs sugar at once and a doctor's review.

Typical adult cut-offs. Read your number against the range printed on your own report, and with a doctor if it is outside it.

Why is the FBS Test done?

• Screening for diabetes and prediabetes
• Symptoms such as excess thirst, frequent urination or weight loss
• Monitoring people already treated for diabetes
• Routine health checkups, especially after age 30 or with a family history of diabetes

What does the FBS Test (Fasting Blood Sugar) measure?

1 parameter. Expand a group to see the measurements, units and available method details.

The reference interval printed on your actual laboratory report governs interpretation. Intervals can vary by laboratory, method, age, sex and pregnancy. Methods can also vary by processing laboratory.

FBS Test: sample & preparation

Sample: Blood. Fasting: Required (8-12 hours).

• Do not eat or drink anything except plain water for 8 to 12 hours before this test. Have the sample taken first thing in the morning if possible, and continue your usual medicines unless your doctor advises otherwise.

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