As you know, keeping your diabetes in good control is the key to staying healthy.  You check your blood sugar levels at different times of the day to make sure your diabetes plan is working (see Blood Sugar Testing brochure).  These tests tell you what your blood sugar level is at that moment, which is very helpful.  However, your blood sugar levels change a lot over the course of a day.  Although self-testing frequently is a good way to manage your diabetes, it ALONE does not give you the whole picture.

There is another test that can tell you your average blood sugar for the past 2 to 3 months.  This test is called a hemoglobin A_1C.  You may hear a few different names for this laboratory test, include:

• HbA1C
• Glycohemoglobin
• A1C

Note: Recently, the American College of Endocrinology (ACE) and the American Association of Clinical Endocrinologists (AACE) recommended that the hemoglobin A1c be referred to as the "A1C".  We will use this reference from here on.

What is hemoglobin?

Hemoglobin is a protein inside your red blood cells.  It is the part of the red blood cell that carries oxygen from your lungs to the rest of your body.  Hemoglobin also carries sugar, because sugars can stick to all kinds of proteins in your body.  Once sugar sticks to hemoglobin, it is stuck there for the life of the red blood cell, about 3 or 4 months.  The more sugar there is in your blood, the more will end up stuck to the hemoglobin.

What does the A1C measure?

A1C is a measure of how much sugar is stuck to your hemoglobin.  Your A1C reading tells you and your healthcare team what your average blood sugar level has been for the past 2 or 3 months.  If you have lots of sugar in your blood and your average blood sugar has been high for the past few months, then your A1C will be high.  The A1C test allows you to see how good your control has really been.  You should talk to your healthcare team about your daily blood sugar tests and your A1C.

*ACE/AACE A1C Target for Glycemic Control

This chart is an example of how blood sugar compare to A1C.  The numbers in this chart are for nonpregnant adults.  "Take action" depends on your own plan, and your action steps should be discussed with your healthcare team.  Some labs use different ways to test and have a different normal range.  Talk to your healthcare team about your results.

How can A1C testing help me?

An A1C higher than 6.5% is a warning sign that your diabetes is out of control.  If your hemoglobin A1C is high, your healthcare team may change your diabetes plan to help control your blood sugar better.  Changes in your plan are expected from time to time and will help bring your A1C closer to normal.  When your A1C is close to normal, you know you are doing all you can to stay healthy.

Research shows that good blood sugar control does lower your risk of developing major diabetes related health problems including heart disease, stroke, kidney disease, eye disease, nerve damage, amputations, and circulation problems.  By keeping your blood sugar close to normal, you will stop or delay the damage high blood sugar does to blood vessels and nerves.  You can prevent the complications of diabetes (see Take-charge Management brochure).

Where do I go for an A1C test?

Some doctors can do an A1C in their office by taking a blood drop from a finger stick.  You can wait for the results and discuss them right away.  You can also go to the lab for this test.

How often should I have an A1C test?

The ACE and AACE recommend that anyone with diabetes should have an A1C done every 6 months for people at or below the target of 6.5%, and every 3 months for those above 6.5%, and every 3 months for those above 6.5% or changing therapy.  If you inject insulin, you should have this test done every 3 months.  Two major studies have shown the importance of good blood sugar control and the relationship of the A1C to diabetes complications.  The first was the Diabetes Control and Complications Trial (DCCT).

In this study, patients with type 1 diabetes had an A1C every month.  This gave the healthcare team useful information to change treatment plans.  In this study, patients who had close to normal A1C study, patients who had close to normal A1C were in better health and had fewer cases of eye disease, kidney disease and nerve damage.

The other study was called the United Kingdom Prospective Diabetes Study (UKPDS).  This was a study done with patients with type 2 diabetes.  People who had good blood sugar control were in better health in this study, too.

Both of these studies show that the hard work it takes to control your blood sugar is worth it.  Your healthcare team will help you take good care of your blood sugar.  They will tell  you how often you should have an A1C.

My A1C target goal is: 6.5%

Maria has type 2 diagetes.  She was testing her blood sugar every morning before breakfast.  Her blood sugars were usually normal, below 100 mg/dL.  She was shocked when she learned her A1C was high (9%).  Maria found out that her morning blood sugar was normal, but her blood sugar at other times of the day was high¹.  She needed to control her morning sugar AND her after-meal and bedtime blood sugar.  With the help of her healthcare team, Maria made changes to her diabetes care plan to help her control her blood sugar.  In fact, Maria was happy to learn that her A1C went down to 7.5% by her next visit, which showed her new plan was really working - all day long.

¹ACE recently recommended after meal blood sugars be kept below 140 mg/dL and pre-meal sugars below 110 mg/dL.