Everything You Need to Know About HbA1c Diabetes Testing

This article contains medical information screened for accuracy by Dr. Gareth Sessel, MD. 

There are several types of tests physicians can order as part of comprehensive oversight for diabetes diagnosis and maintenance, including Fasting Plasma Glucose and Oral Glucose Tolerance tests. Another common assessment is an HbA1c test, which we will review below. 

What is an HbA1c test?

HbA1c tests average blood glucose levels over a period of 2 to 3 months. Physicians can order an HbA1c test to help monitor and manage diabetes in patients. One of the advantages of HbA1c testing is that patients do not need to fast or drink anything beforehand. 

What does an HbA1c test measure?

When a person consumes sugary foods, the sugar is absorbed by the digestive tract and enters the bloodstream. Everyone needs some sugar in their blood, which acts as a fuel and provides their bodies with energy.  Some of this sugar will attach to hemoglobin proteins in red blood cells. Everyone has some sugar attached to hemoglobin, but those with higher blood sugar levels, such as patients with prediabetes or diabetes, have more. The HbA1c test measures the average percentage of sugar-coated hemoglobin within your blood over a period of time. 

Why is it important to test for average blood glucose in diabetes patients?

Testing for average blood glucose is an important part of managing diabetes because it provides critical information about a patient's blood sugar control. Monitoring average blood glucose levels can help reduce the risk of long-term complications of diabetes, such as nerve damage, kidney disease, and cardiovascular disease. 

Is HbA1c the best test for diabetes diagnosis? 

According to guidelines from the American Diabetes Association, certain HbA1c tests can be used to diagnose diabetes. However, Fasting Plasma Glucose (FPG) or Oral Glucose Tolerance Tests (OGTT) are more sensitive methods to diagnose diabetes. FPG tests for fasting blood glucose levels — it is usually performed before breakfast — and OGTT checks blood glucose levels before and two hours after consuming a sweet drink.  

How accurate is HbA1c testing?

HbA1c testing is accurate and considered a valuable tool for monitoring blood glucose levels in people with diabetes. However, HbA1c testing is not recommended for diagnosing diabetes in certain populations, such as children, pregnant women, and people with certain medical conditions. In these cases, other tests, such as fasting plasma glucose (FPG) or oral glucose tolerance tests (OGTT), may be used instead.

What is a normal HbA1c test result? 

Normal HbA1c levels are less than 5.7%. Prediabetes is 5.7% to 6.4%. Diabetes is 6.5% or higher. Higher HbA1C levels are linked to diabetes complications.

Can you perform HbA1c testing at home to monitor diabetes?

HbA1c testing is suitable to conduct outside a medical setting, such as a patient's home. A patient can perform an HbA1c test remotely with the help of a dried blood spot card. In this case, a physician orders a self-collection kit to the patient’s home after a telehealth or in-person office visit, or as part of ongoing medical assessment.   

The self-collection kit usually contains collection devices such as dried blood spot collection card, alcohol pads, gauze pads, single use lancets, bandages, and return pouch. The patient pricks their finger with the lancet and deposits several drops of blood onto the dried blood spot card. Once dry, the patient mails the card to a lab where it is processed by technicians. The oversight physician reviews test results with the patient and recommends follow up care.

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Can remote care improve outcomes for diabetes patients? 

Some evidence suggests that telemedicine may facilitate reducing A1c in patients with type 2 diabetes compared with in-person care or in addition to in-person care. Rural populations in particular may benefit from speciality diabetes care via telemedicine, which has been linked with time savings, high appointment adherence rates, and high patient satisfaction. 

Who should take an HbA1c diabetes test?

The HbA1c test is generally recommended for people who have been diagnosed with diabetes or who are at risk of developing diabetes. It may also be recommended for people who have symptoms of diabetes, such as increased thirst, frequent urination, and unexplained weight loss.

In some cases, an HbA1c test may also be used to screen for diabetes in certain high-risk populations, such as people with a family history of diabetes, overweight or obese individuals, and those with a history of gestational diabetes or polycystic ovary syndrome.

Conclusion: 

HbA1c testing is useful for patients with diabetes and can be used as part of a series of tests that screen for diabetes. For patients with diabetes, monitoring average blood glucose levels with HbA1c testing is important because it can help identify whether a current treatment plan is effective in controlling blood sugar. If average blood glucose levels are high, it may be necessary to adjust medication or make other changes to the patient's treatment plan.

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