All You Need to Know About the A1c Blood Draw

he A1c blood draw is used to detect a person’s average blood sugar levels in the past 3 months. If the A1c level is elevated, this may indicate the presence of prediabetes or diabetes mellitus (DM). However, some conditions could result in inaccurate A1c results. Here is what you need to know about the A1c test.

What is an A1c test?

A1c stands for glycated hemoglobin. It is also known as hemoglobin A1c, HbA1c, glycosylated hemoglobin, and glycohemoglobin.

Hemoglobin is a protein pigment found in red blood cells. It carries oxygen to the different organs in the body. There are several types of hemoglobin, but the most common is hemoglobin A.

As blood transports glucose to various organs, glucose attaches to hemoglobin to form glycated hemoglobin. Since red blood cells have an average lifespan of 120 days, measuring the glycated hemoglobin in blood gives an estimate of the average blood sugar levels in the past 3 months.

When is an A1c blood draw needed?

An A1c blood draw is used to diagnose type 2 diabetes mellitus (T2D). If you’re having symptoms of diabetes, such as increased thirst, hunger and urination, your doctor may request an A1c test. Doctors also use the A1c test to diagnose T2D in at-risk individuals with no diabetes symptoms.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) does not recommend using the A1c test for diagnosing type 1 diabetes, gestational diabetes or cystic fibrosis-related diabetes.

The A1c test can also detect prediabetes. Research shows about 34.5% of US adults have prediabetes. If you have prediabetes, you have a higher chance of developing T2D.

In the 2021 standards of care guidelines, the American Diabetes Association (ADA) recommends screening for prediabetes and diabetes in all adults aged 35 years and above. If you don’t have prediabetes or diabetes, you should repeat the test at least every 3 years.

The ADA also recommends testing for prediabetes or T2D in adults who are overweight or obese who have risk factors for DM, such as:

• A first-degree relative with DM
• Hypertension
• Abnormal cholesterol panel
• Cardiovascular disease
• Polycystic ovarian syndrome
• A history of gestational DM

In addition, African Americans, Asian Americans, Native Americans, Latinos, and Pacific Islander have a higher risk of developing prediabetes and T2D.

The data for the use of A1c in children or adolescents is limited. However, experts recommend diabetes and prediabetes screening using an A1c test in children who are pubertal or at least 10 years old with any of the following:

• Family history of T2D
• Maternal history of gestational DM during the child’s gestation
• High-risk race
• Evidence of insulin resistance

If you have diabetes, the A1c blood test is a valuable tool for blood sugar monitoring. Uncontrolled blood sugar levels put you at risk for developing complications. If your blood sugar levels are good and stable, you will need A1c testing twice a year. But if your blood sugar control is suboptimal, you may need to do the tests every 3 months. Maintaining your target A1c levels is essential to preventing and delaying the onset of diabetes complications.

How to prepare for an A1c test

The A1c test is convenient and does not need special preparation. It can be done at any time. Eating or drinking does not affect the result, so there’s no need to fast before testing.

When you go for testing, a blood sample may be collected from your vein and sent to the lab. Another method (point of care test) uses blood from a finger prick to get a same-day result. However, point-of-care tests are best avoided when seeking a diagnosis. Instead, blood should be drawn and sent to the lab. It’s okay to use point-of-care testing for monitoring.

A1c test results explained:

According to the NIIDK, other factors might have interfered with the result if the A1c level is below 4% or above 15%. Studies suggest very low A1c levels may represent an increased risk of having a liver disease or dying. Your doctor may request further investigations if you have values below 4%. Similarly, high A1c levels are dangerous and increase your odds of developing complications.

Experts recommend a target A1c < 7% if you are receiving diabetes treatment. But if you cannot safely achieve this target because of a high risk of dangerously low blood sugar levels, your doctor may suggest a higher A1c target of < 8%.

Estimated average glucose

The A1c test is calculated in percentages, but the lab may report it as estimated average glucose in mg/dl, just like the home glucometer. An estimated average glucose makes it easier to understand your sugar control. The table below is a guide.

Causes of a false A1C test result

There can be considerable variability in results, so experts recommend using an NGSP-certified and standardized assay. Standardized assays have helped improve the accuracy of test results.

Because the A1c test measures glucose bound to hemoglobin A, people with other hemoglobin variants may have inaccurate results. Hemoglobin variants that might interfere with the hemoglobin A1c assay are hemoglobin C, S, E, D, and F. If you have a hemoglobin variant, it is still possible to have an A1c test. Some assays do not show interference with specific hemoglobin variants, and your doctor can request specifically for those assays.

Other causes of inaccurate A1c test results are:

• Hemodialysis
• Recent blood loss or blood transfusions
• Medications like erythropoietin and some HIV drugs
• Second and third trimester of pregnancy
• Low iron levels

Alternatives to the A1c blood draw

Other tests useful in determining the average blood glucose are fructosamine, glycated albumin, and 1,5-anhydroglucitol. The fructosamine and glycated albumin reflect the average blood glucose in the preceding 2–3 weeks. 1,5-anhydroglucitol shows the average blood glucose in the preceding 1–2 weeks.

Alternative diagnostic tests are fasting plasma glucose (FPG) or oral glucose tolerance test (OGTT). Unlike the A1c test, these tests require special preparations. However, the A1c test is less sensitive than the FPG and OGTT. This means it detects fewer cases of diabetes than the FPG and OGTT.

Importance of the A1c test

If you have diabetes, a high A1C test shows you have poor blood sugar control. A high A1c test result means you have a higher chance of developing diabetes complications such as nerve damage, visual disturbances, kidney disease, and cardiovascular disease. This makes blood sugar monitoring critical in your treatment plan. The A1c test is an excellent tool in the continuing management of diabetes.

People with high hemoglobin A1c levels also have a chance of cardiovascular disease, even if they don’t have diabetes. In addition, your odds of developing frank diabetes increase with increasing HbA1c levels.

You should discuss unusual HbA1c results with your doctor and work out a plan. This may mean a more intensive lifestyle change or a medication change. An A1c test result that is very different from your blood sugar readings will probably require a reassessment.

No matter your test results, working with your healthcare team and implementing a customized treatment plan will set you up for success.

Source: https://healthnews.com/