18/10/2025
Can HbA1c accurately indicate blood glucose levels?
The HbA1c measures how much sugar is stuck to a hemoglobin molecule.
So the A1c does not measure blood glucose levels.
So the short answer is: No.
With that said, the A1c is a valuable tool to measure the average blood glucose levels for the last 3 months. Why?
Most people know that hemoglobin is used by red blood cells to transport oxygen throughout the body. However, people don’t realize that hemoglobin is a versatile molecule; it can act as a buffer to balance the pH and glucose levels of the blood.
So if blood sugar levels are high, hemoglobin can attach to the extra sugar.
Once the hemoglobin (HbA - the type of hemoglobin most people have in their body) attaches to the glucose (1c - organic chemistry lingo to indicate an extra carbon molecule from sugar attached itself to the first carbon atom in hemoglobin), you get a glycated hemoglobin molecule, HbA1c (HbA + 1c = HbA1c).
The number we get from the result indicates how many hemoglobin molecules are glycated (6.5% or more is diagnostic for diabetes).
Since the average lifespan of a red blood cell is 3 months and since red blood cells carry the same hemoglobin with them throughout their lives, we can see the levels of HbA1c for the last 3 months.
To summarize:
HbA1c does not directly measure blood glucose levels; or even the average blood glucose levels.
However HbA1c can accurately measure the percentage of glycated hemoglobin molecules.
Since they’ve likely been around for at least 3 months, we can gain insights into how high or low the blood sugar levels have been throughout that time.
I hope this helps.