An increased blood glucose (sugar) level is one of the most important health concerns in today’s time, especially with people living with prediabetes or diabetes. The HbA1c test is one of the most accurate methods to monitor and manage these conditions.  This test reports the average level of sugar present in your bloodstream and on glycated (covered) red blood cells over the past three months, which is the average lifespan of red blood cells. Since the HbA1c test gives results as a percentage value, it is often difficult for the general public to interpret. 

In this article, learn about how you can convert your current blood sugar level to the HbA1c percentage value at home using a HbA1c calculator.  Also, learn about the blood sugar levels of some of the common HbA1c values and the limitations to be mindful of when using HbA1c calculators.

Normal HbA1c Level Chart:

The HbA1c test reports the blood sugar level in percentage value. According to the American Diabetes Association (ADA) and the National Institute of Diabetes, Digestive and Kidney Disease (NIDDK), the normal blood sugar levels for non-diabetic, diabetic, and prediabetic groups when tested with HbA1c tests is summarized in the chart below:

Blood Sugar Chart Levels:
Healthy (Non-Diabetic) Less than 5.7%
Prediabetic 5.7-6.4%
Diabetic 6.5% and higher

HbA1c % Calculation Using a HbA1c Calculator

The estimated average blood sugar levels are calculated in the HbA1c test in percentage value. There are many calculators available on the internet that use a simple formula to calculate your HbA1c percentage from a blood sugar reading taken from your CGM or glucometer. 

To convert the values of blood sugar levels (mg/dL) to HbA1c percentage value, you can use a formula manually or use the calculator below:

Conversion Formula of Blood Glucose (mg/dl) to HbA1c(%):

The formula for conversion of an at-home blood sugar reading to HbA1c is:
HbA1c (%) =Estimated Average Glucose (mg/dL) + 46.7) / 28.7

For example, if a person’s blood sugar level is 140 mg/dl, their HbA1c % would be as follows:
140+46.7=186.7 / 28.7= 6.5%

Drawbacks of Using an Online HbA1c Calculator

An HbA1c calculator can help people living with prediabetes and diabetes understand the connection between daily readings and longer-term results. These calculators, however, are imperfect and have significant drawbacks. 

Online HbA1c calculators can provide only rough estimations, because HbA1c tests and daily glucose monitoring are looking at different parameters. While HbA1c tests assess average blood sugar over three months, CGM’s and glucometers measure blood sugar levels in the moment and can detect sudden, short-term changes and high/low blood sugar events. This means your latest blood sugar reading may not reflect your long-term average blood sugar levels. Additionally, HbA1c test results can be affected by a number of health conditions, such as medications, blood loss, pregnancy, and conditions that affect your hemoglobin (eg. anemia). It’s also important to remember that an HbA1c calculator cannot replace an HbA1c test or daily blood sugar monitoring, and it should not be used to make treatment decisions.

Blood sugar levels are important parameters that should always be monitored and controlled daily, especially if you are living with prediabetes or diabetes. The HbA1c test is one of the most accurate tests that should accompany daily glucose readings for optimal health information.

Now that you know how to convert your blood sugar readings into an HbA1c percentage, you will more easily and effectively be able to monitor the condition for yourself, and to make more educated decisions regarding your health and well-being! 

Knowledge is power! 

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