What Is the Difference Between My A1c and the Numbers on My Glucometer?

July 10, 2018

When your doctor says you have prediabetes or type 2 diabetes, it’s usually because of your A1c test result. If your A1c is over 5.7 but below 6.4, you like have prediabetes. If it’s over 6.5 on two or more tests, you likely have type 2 diabetes.

You will get a glucometer with your first prescription of test strips and fingersticks. The doctor will tell you to aim for readings between 80 and 130 before a meal and under 180 after a meal. And if you are like most people, you will wonder how to make sense of all this new information.

Why the Two Measures of Blood Sugar?

Blood sugar, or glucose, is generally measured in two ways. The first way is usually done in a lab and tells your doctor about your HbA1c, or often just referred to as A1c. This measurement is a percentage of hemoglobin that is bound with glucose in your blood.

Hemoglobin, abbreviated as Hb, is the part of the red blood cell that carries oxygen to your cells. Glucose, which is also used by cells for energy, hitches a ride on the hemoglobin, and with the help of insulin gets into your cells, where it is used for energy or stored.

The more hemoglobin with glucose attached, also called glycated hemoglobin, circulating in your blood, the higher the percentage of these glucose-bound red blood cells. Thus, your HbA1c is a measure of the percentage of these glycated hemoglobin cells in the blood.

The second way blood sugar levels are measured is in terms of weight per volume. A gram is equal to the weight of 16 drops of water and a milligram is one-thousandths of a gram. A deciliter is one-tenth of a liter. Thus, glucose reading on your glucometer of 100 is 100 milligrams of glucose per deciliter of plasma.

What Does A1c Tell Me About Blood Glucose?

Your doctor is interested in your A1c, or the amount of glycated hemoglobin in your blood, because it reflects your average blood glucose levels over the past three months. The normal average range for A1c varies with age and many other factors, but in general, for most otherwise healthy adults, the range is below 5.7 percent, and for people with diabetes it is between 5.7 percent and 7 percent.

What Does My Glucometer Tell Me About Blood Glucose?

Your glucose meter will show you how much glucose is in your blood at the moment you prick your finger and sample the drop of blood. Using a glucose meter is a way to see the effects of the foods you eat, the amount of exercise you do, and the medications you take to manage your blood sugar.

Many people with diabetes aim to keep their blood sugar levels as close to the normal range as possible, which is around 80 milligrams per deciliter before a meal and less than 180 mg per deciliter two hours after a meal. You and your doctor will determine the best target range for you.

If you are of African, Mediterranean, or Southeast Asian descent, you may have what is called a hemoglobin variant, which can make the A1c test unreliable for diagnosing and monitoring diabetes. Likewise, people with sickle cell anemia or thalassemia may not get accurate results from the A1c test. The National Glycohemoglobin Standardization Program (NGSP) has developed information for diabetes healthcare providers about which hemoglobin tests to use for patients with such variants.

Resources for Understanding Blood Glucose

If you would like more information about measuring and monitoring your blood sugar, here are three useful resources:

• The A1c Test & Diabetes, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
• Managing Diabetes (NIDDK)
• What is Insulin, Endocrineweb

At Healthcare Associates of Texas, we work with you to find the optimal treatment needed for your health. We offer an integrated approach to your care with primary care and diabetes specialists working together to ensure that you stay on track to reach your A1c goals while enjoying your life. Call our Appointment Line at (972) 258-7499 or contact us by email.