What does HbA1c mean? A diabetologist explains
If you or a family member has diabetes — or your doctor suspects it — you've probably seen “HbA1c” on a lab slip. It is the single most important number in diabetes care, yet most patients are never told what it actually means. Here is the plain-language version I give my own patients.
HbA1c is your three-month sugar average
Glucose in your blood naturally sticks to haemoglobin, the protein inside red blood cells. The more sugar in your blood, the more of it gets stuck. HbA1c (glycated haemoglobin) measures what percentage of your haemoglobin has sugar attached.
Because red blood cells live for about three months, HbA1c reflects your average blood sugar over roughly the past 8–12 weeks. That is what makes it special: a fasting sugar tells me about one morning; HbA1c tells me about your whole quarter.
What the numbers mean
- Below 5.7% — normal.
- 5.7% to 6.4% — prediabetes. Your sugar is running higher than it should, but there is still time to reverse course with diet, activity and weight management.
- 6.5% or above — in the diabetes range. Your doctor will usually confirm with a repeat test or a sugar reading before making the diagnosis.
For people already living with diabetes, the target is individual — commonly below 7%, but your doctor may set it higher or lower depending on your age, other conditions and risk of low sugar. Don't chase a number you saw online; chase the one your doctor set for you.
Why one high reading isn't the full story — and one good reading isn't either
Patients often eat carefully for two days before a sugar test and feel relieved by a good fasting number. HbA1c is honest: it averages the festival sweets, the skipped walks and the good weeks alike. The reverse is also true — a single high random sugar after a heavy biryani does not mean your control is poor. This is exactly why doctors rely on HbA1c to judge how treatment is really going.
How often should you test?
- Living with diabetes: every 3 months if treatment is being adjusted or targets aren't met; every 6 months once stable.
- Prediabetes: at least once a year, alongside lifestyle changes.
- Family history of diabetes, over 35, or overweight: screening every 1–3 years is sensible — diabetes is silent in its early years.
A few things that can affect the result
Because the test rides on red blood cells, conditions that change those cells — significant anaemia, recent blood loss or transfusion, some haemoglobin variants — can nudge HbA1c up or down. If your HbA1c doesn't match your home sugar readings, tell your doctor; a simple CBC and iron check often explains the gap.
The practical bits
No fasting is needed — you can walk in any time of day. It's a simple blood sample, the report is ready the same day, and at Caspian it costs ₹600 with free home collection on orders above ₹500. If you're due for a fuller review, our Comprehensive Diabetes Screening (₹899) pairs HbA1c with cholesterol and early kidney checks — the complications worth catching early.