HbA1c vs Fasting Glucose - what's the difference?
Both measure blood sugar, but differently: HbA1c is a ~3-month average, fasting glucose is a snapshot. Here's when each matters.
HbA1c
Glycated hemoglobin - the share of hemoglobin "sugar-coated" over the last ~2–3 months. Reflects your average sugar, independent of your last meal.
Fasting glucose
Your blood-sugar level at a single moment, usually after 8+ hours fasting. Changes quickly with food, stress and exercise.
Key differences
- HbA1c averages ~3 months; fasting glucose is a point-in-time snapshot.
- HbA1c needs no fasting; fasting glucose does.
- Glucose is sensitive to your last meal and stress; HbA1c isn't.
- A diabetes diagnosis is often made using both together.
Bottom line
It's not either/or: HbA1c gives the long-term picture, fasting glucose the current one. Your doctor usually looks at both.
Frequently asked questions
Which is more accurate for diabetes?
Both are valid and complementary. HbA1c is more convenient (no fasting, more stable), while fasting glucose catches acute changes.
Can HbA1c be normal while glucose is high?
Yes, after a recent sugar spike - HbA1c hasn't "caught up" yet. That's why they're read together.
Read more
Have both on your report? Upload it and Mediora explains each in context.
Upload a test - freeMediora.AI is an informational tool - interpretation, not a diagnosis. Always discuss decisions with your doctor.