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A medical professionals hands in white latex gloves administering a fingerprick glucose test to a hand placed on a table
A medical professionals hands in white latex gloves administering a fingerprick glucose test to a hand placed on a table

Whether you’re noticing symptoms of blood sugar spikes becoming more frequent or you simply want to learn more about your glucose, understanding what optimal A1C levels are and what affects these levels can help you make better choices for your metabolic health. 

In this article, we’ll review what the A1C test measures, who it may be helpful for, and how you can set goals for improving your A1C level.

The A1C Test: What is it? 

HbA1C is a medical term that refers to glycated or glycosylated hemoglobin. Hemoglobin is a protein found within red blood cells, and glycated hemoglobin refers to the hemoglobin that is attached to glucose. 

The lifecycle of red blood cells spans from about 8 weeks to 12 weeks, so your A1C levels are a reflection of blood glucose levels over the past three months.

An A1C test measures the percentage of your red blood cells that have sugar-coated hemoglobin, and since it measures the average value over a three month period, it can help uncover trends in your overall glucose levels.

Why Should I Get the A1C Test?

Woman checking lab results on phone

Measuring glycated hemoglobin through the A1C test is a valuable tool in understanding the bigger picture when it comes to your body’s glycemic control. Because red blood cells live for up to three months, the A1C test can provide helpful insight into the bigger picture of your body’s glycemic control as well as metabolic health.

Whereas the finger prick method of testing your blood sugar captures a snapshot of where your glucose levels are in that exact moment, the A1C test estimates a two to three month average of your blood glucose values.

While the finger prick test may shed light on how your blood glucose levels fluctuated when you skipped breakfast that morning, for example, it won’t provide much insight into your overall glucose trends. 

Alongside the A1C test, a continuous glucose monitor can allow for real-time tracking of glucose over large windows, capturing not only the fluctuations the A1C may miss, but also the trends over time that the single finger-stick may miss.

Diagnosing Prediabetes and Type 2 Diabetes With the A1C Test

HbA1C levels are used as a diagnostic tool for diagnosing type 2 diabetes (as well as prediabetes). The A1C test is generally the preferred method of screening for and diagnosing diabetes for several reasons, including:

  • It does not involve special instructions or requirements (such as fasting). 
  • It can be done at any time of the day. 
  • The results are not altered by acute factors such as stress or exercise.
  • It is considered more convenient than the oral glucose tolerance test and the fasting plasma glucose test.   

The A1C test can also have a nearly identical sensitivity for predicting diabetic retinopathy. This means the test can be a valuable tool and effective in “picking up” how likely someone may develop diabetes-induced retinopathy. 

It’s interesting to note that in some cases the A1C test can detect glucose levels that correspond to diabetes where the fasting blood glucose test has failed to do so, and vice versa. 

Using A1C for Elevated Blood Glucose Levels

Doctor explaining A1C test results to patient

If your A1C is elevated, you’ll want to work with your doctor or a medical professional to set an A1C goal based on your individual health needs. Your doctor may specify a certain value based on where your levels currently are and advise certain lifestyle changes that may be helpful in lowering your A1C value over time.

Many lifestyle and dietary changes can take time to have any observable impact on your blood glucose levels. As you and your doctor work to improve your blood glucose levels, you may want to make sure you are regularly monitoring your A1C.

Certain medications for diabetic glycemic control have been observed to take effect in less time for some people. If you have elevated A1C levels, you may want to discuss this option further with a medical professional to determine the best options for you and your health.

Limitations of A1C

It’s also important to understand the limitations of the A1C test. For example, some conditions such as anemia can alter the turnover of your red blood cells, leading to more glucose exposure and higher A1C levels as a result.

Other factors such as certain medications, high alcohol consumption, or even blood transfusions have all been observed to falsely elevate A1C levels in some cases. Conversely, factors such as pregnancy, vitamin C, or vitamin E ingestion have been observed to cause falsely decreased A1C levels reflected in tests.

If you’re concerned about your A1C levels, you may want to consider pairing this test with other forms of glucose measuring and discuss your results with your doctor.

What are the Updated Guidelines for A1C?

Blood test vial

According to the ADA, a diagnosis of diabetes can be made if HbA1C levels are 6.5 percent or higher. Ranges between 5.7 to 6.4 percent are considered high risk for diabetes. Individuals with HbA1c levels between 6 and 6.5 percent are considered an even higher risk, and may be advised to undergo other forms of testing by the doctor.

An A1C level below 5.7 percent is considered normal. Some practitioners may set an “optimal range”, however, there isn’t strong evidence to support any one range as being optimal at the present time. 

This is because the A1C test may be prone to certain inaccuracies, and various factors such as chronic blood loss or more serious conditions such as splenomegaly can influence the results and lead to false results. This may be one reason why, as discussed earlier, other tests can be more effective in diagnosing diabetes (although each has their own drawbacks). 

For example, some research has suggested that HbA1C levels that read between 6.0 to 6.5 percent may have a relatively higher rate of false positive or false negative readings and should be combined with other lab values for full assessment, such as a fasting glucose reading.

A1C Target: What Should my A1C Goals be? 

Your A1C goals will depend on your current A1C levels, lifestyle, and current nutritional habits. These goals are typically set by you and your doctor after discussing these factors and determining what a realistic goal should be. Your doctor may also help you determine a realistic timeline for reducing your A1C levels. 

Ideally, your goal may be to bring your A1C levels within the normal range, and ultimately work towards keeping it between 5 to 5.4 percent. 

Understanding A1C Percentages 

Understanding A1C percentages: normal - below 5.7%, prediabetes - 5.7-6.4%, diabetes - 6.5% or above

Your A1C is calculated using the following formulas:

  • As a percentage: A1C = (Estimated average glucose(mg/dL) + 46.7) / 28.7 
  • As a measurement of mmol/mol: A1C = 10.929 * (A1C(%) - 2.15)

Check out our A1C calculator here.

A1C Goals for Those Without Diabetes 

If you’re in the very high risk group for developing diabetes (A1C levels between 6 to 6.5 percent), your initial goal may be to reduce your A1C enough to fall outside of the prediabetes threshold, which ranges from 5.7 percent to 6.4 percent.

For those that are around the upper limit between 5.5 to 5.7 percent, you may want to aim to gradually lower your levels to the optimal range of 5.4 percent or lower.

A1C Goals for Those with Diabetes

The ADA recommends that individuals with diabetes aim for an A1C level of less than 7 percent. If you’ve been diagnosed with type 2 diabetes, you should work with your doctor to implement healthy lifestyle habits that may help your blood sugar response. 

Below, we’ll take you through some evidence-backed tips that may help lower your A1C.

How can I get my A1C down quickly?

Woman stretching legs on mat

In general, there is no quick fix when it comes to lowering your A1C levels. Oftentimes, the most sustainable way to achieve normal HbA1C levels is to incorporate a variety of effective lifestyle habits, dietary changes, and in some cases medications that your doctor has prescribed for you.

Lifestyle habits that can help optimize your blood glucose levels include: 

Dietary changes that can help optimize your blood glucose levels:

It may take several weeks to months for these changes to reflect in your A1C levels. 

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Engage with Your Blood Glucose Levels with Nutrisense

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Heather Davis, MS, RDN, LDN

Reviewed by: Heather Davis, MS, RDN, LDN

Heather is a Registered and Licensed Dietitian Nutritionist (RDN, LDN), subject matter expert, and technical writer, with a master's degree in nutrition science from Bastyr University. She has a specialty in neuroendocrinology and has been working in the field of nutrition—including nutrition research, education, medical writing, and clinical integrative and functional nutrition—for over 15 years.