Understanding HbA1c test results by age and the connection with diabetes

This article looks at the importance of HbA1c testing; explains HbA1c levels, including what are considered normal hb1ac levels for different age groups; and provides information on how understanding HbA1c test results can help you manage your blood sugar levels.

Understanding HbA1c test results by age and the connection with diabetes
Do not index
Do not index
The HbA1c test, or hemoglobin A1c test, is a simple blood test that measures your average blood sugar level over the past two to three months. It's one of the tests used to diagnose pre-diabetes and diabetes mellitus, and it’s a primary test for monitoring how well diabetes is being managed.
In addition to being an important and reliable indicator of long-term glycemic control, HbA1c levels provide valuable information about the risk of long-term complications from diabetes. Elevated HbA1c levels are also regarded as a risk factor for coronary heart disease and stroke, regardless of whether a person has diabetes.

What is diabetes?

Insulin is a hormone, produced in the pancreas, that helps your cells metabolize glucose in the blood so your body can use it for energy. Insulin also signals the liver to store blood sugar for later use. Diabetes is a condition in which this process malfunctions. There are two types of diabetes — type 1 and type 2.

Type 1 diabetes

If the pancreas fails to produce sufficient insulin, not enough glucose will be metabolized, and excess glucose will accumulate in the bloodstream. This is type 1 diabetes, which is typically a lifelong condition that first appears in childhood. Scientists believe that the condition is triggered by a combination of genetic and environmental factors. It is treated with daily insulin injections.

Type 2 diabetes

Eating a diet that is high in sugar and carbohydrate-rich foods for an extended period of time stimulates the production of high levels of insulin to manage glucose utilization and storage. This continual overproduction of insulin may lead to insulin having less and less effect over time — this state of insulin resistance is considered prediabetes.
Insulin resistance tends to worsen over time. The pancreatic beta cells that make insulin can wear out, and the pancreas will no longer produce enough insulin to overcome insulin resistance. When this happens, just as with type 1 diabetes, not all blood glucose can be metabolized, and it accumulates in the bloodstream. This is type 2 diabetes.
Initial treatment tends to involve changes to your diet as planned weight loss early on after diagnosis can even reverse the disease. Then, depending on the response of your blood glucose levels, medication such as metformin can be prescribed. Metformin works by lowering glucose production in the liver and improving the body's sensitivity to insulin so it uses insulin more effectively.
If not properly treated, diabetes can cause serious health complications, including:
  • Nerve damage
  • Impaired vision
  • Impaired hearing
  • Kidney disease
  • Heart disease

What is HbA1c?

HbA1c is also known as glycated hemoglobin. It is produced when your body can’t use all the glucose in your blood. This excess glucose attaches to hemoglobin, the protein within red blood cells that are responsible for circulating oxygen throughout our bodies.
This chemical bonding, or glycation, occurs when excess blood glucose reaches a particular level over an extended period of time. A principal cause of this glucose buildup is insulin resistance, which can lead to prediabetes and then to diabetes.
Because a buildup of glucose in the blood leads to the formation of HbA1c via glycation, testing for the presence of HbA1c will reveal whether there is excess glucose in the blood, and will provide evidence about a person’s average blood glucose levels during the previous two to three months.
Red blood cells circulate through our bodies for only around three months before being replaced by fresh, unglycated cells. Therefore, the test reflects blood glucose levels for the previous twelve weeks or so, which is why the reading is taken quarterly.
HbA1c tests enable accurate diagnoses of both type 1 and type 2 diabetes, as well as prediabetes. They also allow people who have already been diagnosed with diabetes to proactively manage their health and avoid complications of diabetes.

What are healthy HbA1c levels by age?

Your HbA1c level reflects your average glucose level for the past two to three months. Different metrics are used to describe HBA1c levels — you may see them quoted as a percentage or millimoles per mol (mmol/mol).
Research suggests that a normal HbA1c range is 20 to 38 mmol/mol (4.0% to 5.6%). This range indicates that the person has no current risk of developing diabetes. Values between 39 and 46 mmol/mol (5.7% to 6.4%) point to prediabetes. For people who have diabetes, an ideal HbA1c level is 53 mmol/mol (7.0%) or lower.
Recommended blood sugar levels by age group:
Age Group
Normal HbA1c %
HbA1c with possible prediabetes %
HbA1c with diabetes %
HbA1c target with diabetes %
Children and adolescents
Less than 5.7
6.5 or above
7.0 or less
Less than 5.7
6.5 or above
7.0 or less
Adults over 65
Less than 5.7
6.5 or above
8.0 or less

What affects HbA1c levels?

HbA1c levels can be affected by more than just diet — stress, medication, illness, and lifestyle factors can all have an impact as well.
Several factors can increase or decrease your HbA1c level, including:
  • Early-stage or late-stage pregnancy
  • Blood loss or blood transfusions
  • Kidney failure, liver disease, or severe anemia
  • A less common type of hemoglobin that people with certain blood disorders, such as sickle cell anemia and thalassemia have, and some people of African, Mediterranean, or Southeast Asian descent
  • Certain medicines, including opioids and some HIV medications
Unusually low levels of HbA1c are less common than high levels. They may indicate lifestyle factors or conditions that affect blood cell count. These might include:
  • An overly restrictive diet
  • Excessive use of antibiotics and some other drugs
  • Alcoholism
  • Liver disease
  • Recent blood loss or donation
  • Genetic abnormalities

The HbA1c test

Who should get tested and how often?

Knowing your HbA1c level and what you can do to lower the amount of excess glucose in your blood will help you reduce your risk of complications. People with diabetes are usually recommended to have an HbA1c test every three to six months — every three months when newly diagnosed, and then every six months once blood glucose levels have stabilized.
However, it’s also a good idea to get a baseline HbA1c test if you’re an adult without diabetes but over age 45, or if you’re under 45, overweight, and have one or more risk factors for prediabetes or type 2 diabetes:
  • If your result is normal but you’re over 45, have risk factors, or have ever had gestational diabetes, repeat the test every three years.
  • If your result shows that you have prediabetes, your healthcare provider will advise you about important steps you can take to improve your health and lower your risk for type 2 diabetes. With lifestyle changes, prediabetes is reversible. You should also repeat the HbA1c test as often as your doctor recommends, usually every one to two years.
  • If you don’t have symptoms but your result shows that you have prediabetes or diabetes, get a second test on a different day to confirm the result.

How is the test administered?

The HbA1c test is taken via a blood sample in the arm or by finger prick. The sample is sent to a laboratory, where the amount of glycated haemoglobin present in the blood is assessed.
Detection is straightforward, so the amount of blood taken for the sample may be quite small — typically, no more than a few droplets is required from children.

Limitations of the HbA1c test

Like most testing procedures, HbA1c tests are not 100% accurate. Here are some potentially complicating factors:
  • A spike in blood sugar levels in the run-up to the test can overshadow levels in the preceding weeks, distorting the assessment. Some illnesses, for example, can cause a temporary elevation in blood sugar levels.
  • Pregnancy may lead to inaccurate HbA1c readings.
  • Anemic patients often have abnormally low haemoglobin levels, preventing accurate test results.

How to avoid or manage type 2 diabetes by monitoring HbA1c levels

Once you know your HbA1c level, it’s important that you understand what the results mean and how to prevent excess glucose from accumulating in your blood. Even a slightly raised HbA1c level can indicate that you are at risk of prediabetes, diabetes, or other serious health complications. If you are diagnosed with prediabetes, your doctor will likely recommend lifestyle changes, as in many cases, prediabetes is reversible. If you have diabetes, monitoring your HbA1c level, making sure that it stays low, and regular communication with your healthcare provider will help you stay healthy.
Here are some steps you can take to bring your HbA1c level down and then keep it within the target range:

Maintain a healthy diet

A nutritious diet is key to maintaining a healthy HbA1c level. Moderate your intake of sugar and simple carbohydrates, and limit processed foods as these contain high levels of both. Choose a variety of fresh, protein-rich foods. Also eat your calories, don’t drink them — avoid soft drinks and juices, which are high in sugar.

Stay active

Regular exercise and being active in your day-to-day life can help you maintain lower HbA1c levels.

Don’t smoke or vape

Smoking and vaping make it harder for blood to flow around the body and can lead to circulatory issues.

Sleep well

Sleep disorders, whether too little or too much sleep, or a condition such as sleep apnea, are linked to higher HbA1c levels.

Why regular blood sugar monitoring at home is important

HbA1c is an important tool in the diabetes management toolkit, but it doesn’t replace regular blood sugar testing at home. Blood sugar levels go up and down throughout the day and night, and these variations aren’t captured by an HbA1c test.
If you are living with diabetes, understanding how various lifestyle factors and food choices affect your blood sugar levels throughout the day will help you avoid dangerous highs and lows, manage your condition, and stay healthy. Furthermore, your doctor will be able to use the results of blood sugar tests to recommend changes to your treatment.
notion image

Type 2 diabetes remission

Remission is when a person with type 2 diabetes maintains healthy blood glucose levels without diabetes medication. A consistent HbA1c level of 48 mmol/mol (6.5%) or lower is an indicator of remission.
Type 2 diabetes is a serious condition, so achieving remission is an extremely positive outcome.

Lab Testing with Vital

Vital is working with the leading chronic care management companies streamline and scale their lab testing of key biomarkers like HbA1c. With Vital you can turn on lab ordering to labs like LabCorp, Quest and speciality labs in a matter of days rather than months. Whether your users prefer finger prick tests, walk-in appointments or an at-home phlebotomist our APIs and dashboard enable you to do it all.
If you’re looking to launch at-home HbA1c testing speak to our team now.

Written by