What is the FBS Test?
The Fasting Blood Sugar (FBS) test measures the level of glucose (sugar) in your blood after you have not eaten for at least 8 to 12 hours. It is one of the most common tests used to screen for and monitor diabetes.
Why is This Test Done?
- To screen for diabetes mellitus (Type 1 and Type 2)
- To screen for pre-diabetes (impaired fasting glucose)
- To monitor blood sugar control in known diabetic patients
- As part of a routine health check-up
How to Prepare for the FBS Test
Preparation Checklist
- Fast for 8-12 hours before the test. Only water is allowed during the fasting period.
- Do not eat any food, sweets, or chew gum during the fasting period.
- Do not drink tea, coffee, juice, or milk. Only plain water.
- Avoid alcohol for at least 24 hours before the test.
- Continue your regular medications unless your doctor tells you otherwise.
- Best time: Get the test done first thing in the morning (6 AM - 9 AM).
- Tip: Have your last meal before 10 PM the night before, then fast overnight.
What Happens During the Test?
A small blood sample is drawn from a vein in your arm. The procedure takes less than 5 minutes. You may feel a slight pinch when the needle is inserted. After the test, you can eat and drink normally.
Understanding Your Results
| Result | FBS Level (mg/dL) | FBS Level (mmol/L) | What It Means |
|---|---|---|---|
| Normal | 70 - 100 mg/dL | 3.9 - 5.6 mmol/L | Your blood sugar is within the healthy range. |
| Pre-Diabetes | 100 - 125 mg/dL | 5.6 - 6.9 mmol/L | Your blood sugar is higher than normal. Risk of developing diabetes. Lifestyle changes recommended. |
| Diabetes | 126 mg/dL or higher | 7.0 mmol/L or higher | Suggests diabetes. Your doctor will usually confirm with a repeat test. |
| Low (Hypoglycemia) | Below 70 mg/dL | Below 3.9 mmol/L | Blood sugar is too low. May cause dizziness, shakiness, or confusion. Seek medical advice. |
What Should You Do Next?
- Normal result: Continue healthy eating and exercise. Recheck annually.
- Pre-diabetes: Reduce sugar and refined carbohydrates, increase physical activity, lose weight if overweight, and recheck in 3-6 months.
- Diabetes range: Consult your doctor immediately for further testing (PPBS, HbA1c) and a treatment plan.
Important: This information is for educational purposes only. Always consult your doctor for proper interpretation of your test results and medical advice.