Fasting Blood Sugar (FBS)

The Fasting Blood Sugar (FBS) Test is a common and important blood test that measures the level of glucose (sugar) in your blood after a period of fasting (usually 8–12 hours). It is widely used to diagnose and monitor diabetes, prediabetes, and other conditions related to blood sugar regulation.

Types of Blood Sugar Tests

Although Fasting Blood Sugar is one type, it is often part of a group of glucose tests:

• Fasting Blood Sugar (FBS): Measures blood sugar after fasting for 8–12 hours
• Postprandial Blood Sugar (PPBS): Measures sugar levels 2 hours after eating
• Random Blood Sugar (RBS): Can be taken at any time of the day
• Oral Glucose Tolerance Test (OGTT): Measures body’s response to sugar intake
• HbA1c Test: Reflects average blood sugar over the past 2–3 months

Uses of the Fasting Blood Sugar Test

• Diagnosing diabetes or prediabetes
• Monitoring glucose control in people with diabetes
• Assessing response to diabetes treatment
• Part of routine health checkups for those at risk of metabolic disorders
• Helps detect hypoglycemia or hyperglycemia
• Used during pregnancy to screen for gestational diabetes

Preparation

• Fasting Required: Yes — do not eat or drink anything (except water) for 8–12 hours before the test
• Medication: Inform your doctor about any medication you're taking, especially for diabetes
• Hydration: Drink water to stay hydrated; avoid tea, coffee, or sweetened drinks
• Avoid Smoking/Alcohol: Refrain from smoking and alcohol before the test
• Morning Testing Preferred: Typically done in the morning for best accuracy

Frequently Asked Questions (FAQs)

1. What is the Fasting Blood Sugar test?
It measures blood glucose levels after a period of fasting to check for diabetes or glucose metabolism issues.

2. How is the test performed?
A blood sample is taken from a vein in your arm, usually in the morning after overnight fasting.

3. What are normal fasting blood sugar levels?

• Normal: 70–99 mg/dL
• Prediabetes: 100–125 mg/dL
• Diabetes: 126 mg/dL or higher on two separate tests

4. Is fasting mandatory?
Yes, fasting for 8–12 hours is required for accurate results.

5. How often should this test be done?
Annually if you're at risk, or more frequently if you have diabetes or metabolic syndrome.

6. What if my results are high?
Consult your physician for further testing, possible lifestyle changes, or medication.