Past Feature Article

A1C - Is it All I Need to Know About How Well I’m Controlling My Diabetes?

By: Marvin Bouchon, RPh., Drug Information Specialist, Rite Aid Clinical Services

What is A1C?

The term A1C is frequently seen in reference to the management of diabetes and has become the gold standard for measuring glycemic or glucose control. But first, a review of exactly what A1C is. HbA1c (shortened version A1C) stands for hemoglobin (HEE-mo-glo-bin) A1C or glycosylated (gly-KOH-sih-lay-ted) hemoglobin. This test is a measure of an individual’s average blood glucose levels for the previous 2 to 3 months. The numbers reported for A1C are a percentage value. The test indicates the amount of glucose that sticks to red blood cells; more specifically, it indicates the percentage of hemoglobin within red blood cells that have glucose attached. Hemoglobin carries oxygen from the lungs to the rest of the body and is responsible for the red color of our blood cells. Glucose becomes attached to the red blood cells by a process known as glycation (hence the term glycosylated). If an individual’s daily blood glucose is high, then more glucose attaches itself to the red blood cells and the A1C value increases. The higher the glucose level is, the higher the reported A1C number. Hemoglobin A1C is kept relatively current because red blood cells die approximately every 120 days and are replaced by new ones. As a result A1C values are a report of red blood cells with fresh hemoglobin from the last 3 to 4 months.

Why has A1C become so important?

As stated in the opening of this article, A1C has become the gold standard for measuring glucose control. Why has A1C become such a crucial test in assessing a patient’s glucose control? Because the observation of several major studies of patients with diabetes has shown a reduction in diabetic complications per 1% decrease in A1C. This association explains the reason A1C values have become so invaluable in assessing how well a patient is managing their diabetes. The following results of these major studies should bring to light why achieving and maintaining established A1C goals is so important.

Name of Trial	Type of Diabetes Studied	Complication	Decrease in Complication
Diabetes Control and Complications Trial	Type 1	Damage to: Eyes - retinopathy Kidneys - nephropathy Nerves - neuropathy	30% - 35%
Kumamoto Study	Type 2	Damage to: Eyes - retinopathy Kidneys - nephropathy Nerves - neuropathy	30% - 38%
United Kingdom Prospective Diabetes Study	Type 2	Damage to: Eyes - retinopathy	28%
Wisconsin Epidemiology Study of Diabetic Retinopathy	Type 2	Damage to: Eyes - retinopathy Kidneys - nephropathy Nerves - neuropathy Heart and Blood Vessels - cardiovascular disease	20% - 50%

The results of these studies show that some very dramatic decreases in complications occurred as a result of a single 1% reduction in A1C value. This is the reason a reduction of glucose values and the corresponding reduction in A1C has become such a key factor in helping to protect the patient with diabetes from future long term health problems.

Is A1C the only value I now need to know?

Although it is important to pay close attention to A1C values, it does not mean that regular monitoring of glucose is no longer necessary. Several factors regarding glucose control come into play which reminds us that A1C should not be the only value examined when determining a patient’s level of control. Scientists have discovered that everyone’s A1C is not created equal. Two individuals may have similar average blood glucose readings, but will find that their A1C differs. It appears the reason for this difference is glycation (remember, this is the process by which glucose becomes attached to the red blood cells). Some individuals are high glycators and this is reflected in more glucose attachment to hemoglobin cells resulting in a higher A1C level. The reason this difference occurs is currently not known. Additional research to learn more about glycation and how glucose attaches itself to red blood cells is being conducted. Hopefully this research will lead to a greater understanding of how to predict and perhaps treat diabetes. Of interest here is it has also been shown that after meal glucose levels (postprandial glucose levels) seem to be more closely related to HbA1c than before meal/fasting (preprandial) glucose levels. It has also been shown that there appears to be a stronger correlation of after meal glucose levels and both mortality and microvascular effects (effects upon the finer blood vessels in the body). Additional studies have shown that potential adverse effects (upon the kidneys, eyes, circulatory system, blood, and cells) can result from high after meal glucose levels. These observations indicate that in addition to A1C, it is still important to closely monitor daily blood glucose values. In addition there seems to be some importance to after meal glucose values as a predictor of diabetes control.

What is an acceptable number for A1C?

The American Diabetes Association (ADA) provides physicians with a guide for optimum treatment of patients with diabetes. The ADA recommends that patients in general attain an A1C goal of less than 7% and for some individuals as close to normal (less than 6%) as possible without significant hypoglycemia (episodes of low blood sugar).

The American College of Endocrinology has also issued a guideline for A1C. They recommend that A1C be less than or equal to 6.5% which is stricter than the ADA’s recommendations.

A1C is now providing us with a bigger picture of how well a patient is doing with managing his or her diabetes. The value to remember, as recommended by the ADA, is 7% or less (6% for the individual if it can be done without significant hypoglycemia). Check with your physician to determine if these values are appropriate for you.

Your healthcare team can help you achieve your diabetes management goals. Be sure to talk to them about the best way for you to accomplish this. Your Rite Aid Pharmacist is available to help you.