HBA1C AND DIABETES DIAGNOSIS: Everything you need to know

Ever heard of the term HbA1c? If you have diabetes or have a loved one with diabetes, I am sure you have heard your doctor mention it several times. This term is not only important to people with diabetes but also to everyone else, including me and you. We ought to understand what this term means, how it differs from blood glucose levels and its importance in diabetes diagnosis.

HbA1c is also referred to as A1c, hemoglobin A1c, glycated hemoglobin or glycosylated hemoglobin. On this post, we are going to discuss this HbA1c and its role in diabetes diagnosis and management.

What is HbA1c?

This is a blood test. It measures the amount of blood glucose (sugar) attached to hemoglobin in your blood. Hemoglobin is a protein that carries oxygen from the lungs to your body parts. It is part of the red blood cells of your body. When it binds to the sugar in your blood, it is called glycated hemoglobin. If your blood sugar levels are high, more sugar will get attached to the hemoglobin. This will result in high glycated hemoglobin (HbA1c).

Red blood cells of your body live for 2-3 months before they are renewed. The amount of sugar that combines with hemoglobin is directly proportional to your total blood sugar levels at that particular period. That is why the amount HbA1c in your blood shows the average levels of your blood sugar during the last 2-3 months. Therefore, the amount Hba1c in your blood is directly related to the average concentration of glucose in your blood. It gives you an overall picture of your sugar levels for the past 2-3 months. Some people may have very high blood sugars at times and then get very low sugars at times. It is important to note that HbA1c will give you the average levels of blood sugar over that period.

If you have diabetes and your blood sugar levels are constantly high, it means your diabetes is not well controlled. This will reflect in a high HbA1c. It is important to have a normal HbA1c if you have diabetes as higher HbA1c is associated with a greater risk of developing diabetes related complications, like nerve damage, heart disease and many more.

Why is it important?

If you are not already living with diabetes, this test is used to check if you have diabetes or prediabetes. To diagnose type-2 diabetes, HbA1c may be used with other tests like fasting blood glucose. It is not the primary test to diagnose type-1 diabetes and may be used with other tests. These are certain groups of people in which HbA1c cannot be used to diagnose diabetes. Other alternative tests many be used for such groups of people.

If you already have diabetes, HbA1c test, is used by your doctor regularly to monitor the control of your diabetes over a longer period. Random blood sugar tests that are done with a glucose meter will only show your sugar levels for a specific time (the very moment the test is done) whereas HbA1c gives you a picture of the overall sugar control.

Your doctor may use Hba1c to adjust your medication or may advise you on lifestyle changes to work on reducing it to acceptable levels.

When do you need to take an HbA1c test?

If you have diabetes, your doctor will take regular blood tests (mostly 6-monthly tests) to monitor HbA1c levels. You may also do an in-between home A1c test every 3 months in between doctor’s visits.

If you have risk factors associated with diabetes, you need to do this test. These risk factors are as follows:

  • Family history: if you have a close family member with diabetes, you are more likely to develop the condition as well.
  • Belly fat: increased belly fat is another risk factor for diabetes. You have belly fat if you have more fat around the waist than the hips. Your waist circumference should be less than 40 inches if you are male and 35 inches if you are female.
  • Age: age is also a risk. If you are more than 45 years, it is advisable for you to screen for diabetes. This risk increases if you are more than 65 years old.
  • Weight: obesity and being overweight are significant risk factors of having diabetes. A body mass index (BMI) of higher than 25 is not healthy and is associated with insulin resistance.
  • Physical inactivity: lack of physical activity is often associated with weight gain hence diabetes. Exercise increases insulin sensitivity, controls your body weight and reduces your body fat.
  • Gestational diabetes: if you had developed diabetes at some point while you are pregnant or had a baby weighing 9lb (4kg) and above, you are at a higher risk of developing diabetes.
  • Certain ethnic groups: there are certain ethnic groups that are considered to be at a higher risk of developing diabetes. These include Indian- Americans, African-Americans, Alaska Natives, Asians, Latino.
  • Certain health conditions: hypertension or BP >140/90, high triglycerides, high cholesterol, polycystic ovarian syndrome (PCOS) all put you at a high risk of developing diabetes.

You also need to test if you have symptoms of diabetes. These include:

  • Increased thirst
  • Increased hunger
  • Increased urination
  • Losing weight despite eating more
  • Blurry vision
  • Fatigue

How often do you have to test?

This test is generally recommended at least twice in a year (every 6 months) by your health care practitioner. In between doctor’s visits home tests can be done. Be sure to always discuss your home results with your doctor.

For those whose blood glucose remains too elevated, HbA1c can be done more frequently to accommodate treatment changes.

What is your HbA1c level supposed to be?

The normal range for people without diabetes is the level between 4% – 4.6%

You have prediabetes if your HbA1c ranges between 5.6% – 6.4%

You have diabetes if you have levels of 6.5 % or higher.

For those people with diabetes who are using HbA1c for diabetes monitoring, you should aim for levels that are less than 7%

HbA1c %
Normal Below 5.6
Prediabetes 5.7-6.4
Diabetes 6.5 and higher

What do you need to do to reduce your HbA1c?

Poor control for blood glucose is associated with a higher risk of getting complications associated with diabetes. The higher your HbA1c is, the higher your risk of having diabetes-related complications.

Life style changes are the single most important factor in reducing you HbA1c levels. Life style changes generally reduce your blood sugar levels and hence reduce your HbA1c levels. These lifestyle changes include:

  • Exercising regularly: 30mins of brisk walk at least 5 days in a week
  • Losing weight: aim for BMI<25
  • Making healthy dietary choices

Modifications in your medication may also be necessary to bring your levels to a desirable number. This is generally done by your health care practitioner.

Why do I need to lower my levels?

Higher than desirable levels of HbA1c are associated with complications of diabetes such as

  • Nerve damage
  • Heart disease
  • Kidney disease (diabetic nephropathy)
  • Eye problems (diabetic retinopathy

Improving your HbA1c by at least 1% has been proven to reduce your risk of dying by 50%. It has also been proven to cut your risk of diabetes related complications by at least 25%.

Are there different ways to test for HbA1c?

There are two ways to test for your HbA1c levels

Lab Test

The lab test is done at a hospital during your routine hospital visits. A needle is inserted on a vein from your arm to draw up blood. The blood is put into a test tube and sent to the lab for analysis. The results are taken to your doctor for interpretation.

A home test

This test is done in the comfort of your home. It allows you to have a good idea of your HbA1c. It involves you purchasing a home A1c test kit and a small prick on your finger. The test should not be used to replace your visits to the doctor but rather used in-between the visits to help you better control your sugar levels. If you do yearly tests with your doctor, your might do a home test after 6 months as add-on on to your yearly tests. If you do 6 monthly tests, you might want to do 3 monthly home tests. It is important to note that HbA1c is a marker of average control of blood sugar levels for the past 2-3 months; hence monthly tests may not be necessary.

How do blood sugar levels compare with HbA1C readings?

Please note that blood sugar levels fluctuate constantly and HbA1c only gives you an average of these levels for a longer period. The table below shows HbA1c levels against your estimate average blood sugar levels.

HbA1c (%) Average blood sugar (mg/dl) Average blood sugar (mmol/L
5 97 5
6 126 7
7 154 8
8 183 10
9 212 12
10 240 13
11 269 15
12 298 17

When can HbA1c give you false results?

As Hba1c measures the amount of blood glucose that has attached to the hemoglobin, any disease that affects hemoglobin in your body may result in results that are not accurate. These diseases include anemia, sickle cell disease and thalassaemia. If you have one of these diseases and are at risk of diabetes, talk to your doctor who will recommend a different test.

If you ever need a hand or have any questions, feel free to leave them below and I will be more than happy to help you out.

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