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Calculate your average glucose

Average Blood Sugar From HBA1C Calculator

Estimate your 3 month average blood glucose from your most recent HBA1C measurement. Find out what your HBA1C really means.

Average Blood Glucose

101 mg/dl

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How is average blood sugar calculated from your HBA1C?

What is HBA1C?

HBA1C (Glycated hemoglobin) is a form of hemoglobin that is bound to glucose. This is a natural outcome of glucose being present in the blood. Since the average lifespan of a red blood cell is around 4 months the quantity of HBA1C in the blood can be used to measure the average amount of glucose in the blood over the last 3 months. Our normal measurements of blood sugars through finger pricks or CGMs are focused on short timeframes an HBA1C measurement can be a great way to measure the changes to our average blood glucose levels over the long term.

What does your HBA1C measure?

One very common misconception about HBA1C test results is to think the numerical value is a measurement of average blood glucose over the last 3 months. This is particularly common in countries that use the mmol/L measurement units for blood glucose since they are usually in the same range of digits as the % values HBA1C results are often returned in. Even though they look similar, a 5% HBA1C is not equivalent to a 5mmol/L average blood glucose. In fact a 5% HBA1C is equivalent to a 5.4 mml/L average blood glucose. This deviation is magnified the higher the HBA1C measurement for example a 10% HBA1C is equivalent to a 13.3 mmol/L average blood glucose.

Laboratory Specimens in a Vial
Laboratory Specimens in a Vial

Misleading interpretations

This misconception can often lead to diabetics thinking they are keeping their average blood glucose levels closer to normal than they really are. If you understand your HBA1C results correctly they can be a great way to benchmark your blood glucose trends and can give you a clear understanding of your average blood glucose levels compared to normal.

What’s a normal HBA1C result?

The recommended HBA1C level depends on each person and should take into account a lot of different factors. That being said we can look at the HBA1C levels of a non diabetic to get an understanding of what an ideal HBA1C level would be and work backwards from there.

A normal HBA1C for non diabetics is between 4 and 5.6%, which is the same as an average blood glucose of between 3.8 and 6.3. This range covers a fairly wide range of values, but most people would fall in the range of 4.6 and 5.3%.

What does your HBA1C result mean about your average blood glucose?

It’s important to remember that the HBA1C result can be related to average blood glucose. But just like any other average this will smooth out extreme values to somewhere in the middle. That means that an HBA1C of 5% giving an average blood glucose of 5.4mm/L could be the result of many periods of high blood sugar and low blood sugar combined.

How to understand your HBA1C results better

These extreme blood sugars still occur but may be hidden by the averaging effect of the HBA1C measurement. Because of this it’s important to take the HBA1C result in the context of your other direct blood glucose measurements from CGMs or finger pricks. Together these should give you a good background for understanding your HBA1C results and interpreting them as blood glucose levels over time.

Person Using A Glucometer to Measure Blood Glucose Levels
Person Using A Glucometer to Measure Blood Glucose Levels

How is HBA1C relate to average blood glucose levels?

People are often surprised by the average blood glucose calculated from their HBA1C results. Especially for diabetics who rely on finger prick measurements the average blood glucose calculated may be quite different from your average blood glucose reading.

This is usually because of the timing of most peoples readings. Most diabetics tend to look at their levels around meal times or when they are noticing some side effects from hypos or hypers. This gives a skewed perspective of your real blood glucose levels over time. 

A Better Approach

It is also quite hard for people to look at their multiple readings or charts over a period of time and interpret it as an average without calculating it manually. Generally our brains are bad at accurately averaging large datasets like and we are naturally drawn to focus on points of interest like hypos and hypers, giving them extra weight in our minds. This is another reason why a periodic HBA1C measurement can be a great reference point for keeping you on track and gauging your long term movements and patterns.

Calculating your average blood sugars from your HBA1C

You can use the tool above to calculate what your average blood glucose level is from your latest HBA1C. Plug your HBA1C measurement in and the output will show your approximate average blood glucose level over the last 3 months. This is a great way to understand your HBA1C, but keep in mind this is just an approximate average and you should understand it in the context of your day to day blood glucose measurements.