Before we try to understand the HbA1c test, we need to know what HbA1c stands for.
What is ‘HbA1c’?
HbA1c stands for the glycosylated form of haemoglobin.
To understand the glycosylated form of haemoglobin, let us know the forms of Haemoglobin existing in the human body.
| Haemoglobin type | Structure | Frequency in the human body |
| HbA1 | ⍺2β2 chains | 98% |
| HbA2 | ⍺2ẟ2 chains | <2% |
| HbF | ⍺2ɣ2 chains | <2% |
| HbA | ⍺2ε2 chains | Embryonic haemoglobin |
What is the difference between HbA1 and HbA1c molecules of haemoglobin?
HbA1c is the glycosylated form of HbA1 haemoglobin. This glycosylation is the attachment of glucose to the haemoglobin molecule causing adverse effects on the health.
Thus, a high HbA1c level is an indication of high blood glucose or diabetes.
What makes the HbA1c test unique in diagnosing diabetes?
In a fasting blood glucose test or a glucometer based test or a post-meal blood glucose level test, an indication of the ‘current’ or the present blood glucose level is only provided whereas in a HbA1c test, an overall picture of blood glucose levels of over 2-3 months is reflected.
How does the HbA1c test give a 2-3 month blood glucose profile?
The red blood cells have a lifespan of 3 months, the HbA1c test shows an average level of blood glucose for the past 3 months.
Table showing levels of HbA1c corresponding to respective indication of blood sugar concentrations:
| HbA1c levels | Indication | Remarks |
| Below 5.7% | Normal | A range of 4 – 5.7% of HbA1c indicates a normal state of blood sugar levels. |
| 5.7 to 6.4% | Prediabetes | A HbA1c range of 5.7 – 6.4% represents a high risk of diabetes or a state of prediabetes. |
| 6.5% or higher | Diabetes | A range of > 6.5% of HbA1c levels indicate diabetic levels of blood sugar. |
The lifespan of a red blood cell is 3 months, it is important for people with diabetes to get the HbA1c test every 3 months to ensure their blood glucose levels are in control.
Advantages of choosing the HbA1c test:
- Stable reflection of blood sugar – results are obtained irrespective of the effect of the recent meal on glucose levels.
- No dietary restriction required prior to testing.
- Results are unaffected by factors like stress or exercise.
- Single sample is enough since a glycosylated haemoglobin molecule is a stable molecule.
- Testing can be done at any time during the day.
Key takeaway
The HbA1c test gives a clear profile of blood glucose is an accurate way to diagnose diabetes as compared to other methods of testing.
If you’re diabetic, ensure that you get the HbA1c test every 3 months to keep the blood sugar levels in check.
It is recommended to get the HbA1c test to not only get tested for diabetes but also to predict complications that are linked with prolonged levels of high blood glucose.
