Blood sugar tests show how much glucose is in your blood. Together they are used to diagnose and monitor diabetes.
Why this test is done
- Diagnose diabetes and prediabetes
- Monitor how well diabetes treatment is working
- Screen people who have risk factors but no symptoms
How to prepare
- Fasting blood sugar requires about 8 to 10 hours without food; water is allowed
- The post-meal (PP) sample is taken exactly two hours after starting a meal
- HbA1c needs no fasting and can be done at any time of day
- Take your usual medicines unless your doctor tells you otherwise
Understanding your results
- Fasting sugar below 100 mg/dL is normal; 100 to 125 mg/dL is prediabetes; 126 mg/dL or above on two occasions suggests diabetes
- HbA1c below 5.7% is normal; 5.7 to 6.4% is prediabetes; 6.5% or above suggests diabetes
- HbA1c reflects average sugar over roughly three months, so it is not affected by what you ate yesterday
- A single abnormal result is usually confirmed with a repeat test before diabetes is diagnosed
Read your report with your doctor
Reference ranges differ between laboratories, and a value slightly outside the range is often normal for you. What matters is the pattern across your results, your symptoms and your history — which is why the report belongs in a consultation, not a search box.
Frequently Asked Questions
What is the difference between fasting sugar and HbA1c?
Fasting sugar is a snapshot of your blood glucose at that moment. HbA1c reflects your average blood sugar over about three months, so it is not affected by a single meal or a single good day.
Do I need to fast for an HbA1c test?
No. HbA1c can be done at any time of day, with or without food, because it reflects your average blood sugar over roughly three months rather than the level at that moment. Only the fasting sugar sample needs an empty stomach.
What is a fasting blood glucose test?
A blood sample taken after about 8 to 10 hours without food, usually first thing in the morning. It shows your blood glucose at its baseline, before any meal has raised it. Plain water during the fast is allowed.
Can I drink water while fasting for a blood sugar test?
Yes, plain water is allowed and is worth drinking — being dehydrated makes the blood draw harder. Tea, coffee, milk, juice and sweetened drinks are not, as they will affect the result.
Should I take my diabetes medicines before the test?
Take your usual medicines unless your doctor has told you otherwise, and tell the laboratory what you have taken and when. Skipping a dose on your own to make a reading look better defeats the purpose of the test.
What this costs, and what is free
Routine blood tests are generally free at government hospitals and health and wellness centres when ordered there.
Private lab prices for the same test vary widely between cities and between labs in the same city. It is worth asking the price before agreeing, and worth asking your doctor which tests are genuinely needed rather than accepting a bundled package.
Source: Ayushman Bharat PM-JAY, National Health Authority
Prices and scheme rules change. Confirm current details with the hospital or Kendra before you rely on them.