A1c Lab Value

For more than thirty years there has been a valuable blood test that doctors use for their patients with diabetes which measures the average sugar level in the bloodstream for the past three to four months. This test is goes by many names but is commonly referred to as the hemoglobin A1c test, glycosylated hemoglobin (HbA1c) or simply the A1c.

The American Diabetes Association recommends that all patients with diabetes get an A1c test every four months and that they know what the results means. There are a large number of patients with diabetes who have never heard of this test, much less what it means.

Here’s how it works. The A1c test measures the percentage of blood hemoglobin that has sugar molecules bonded onto them. Sugar attaches itself to hemoglobin in proportion to the total sugar in the blood.

Hemoglobin is what carries oxygen in the bloodstream to our tissues. The sugar only comes off when the red blood cell itself dies and then the hemoglobin is recycled by our body. New red blood cells are constantly being produced as old red blood cells die. This recycling process takes about 90 to 120 days to completely turn over all the hemoglobin molecules in the body. The A1c level is considered a reflection of the average blood sugar level during that past 90 to 120 day period.

The A1c result is expressed as a percentage, although that part is often dropped in discussions. The normal A1c range for people without diabetes is between 4.0 and 6.0 percent. These assay values typically vary slightly from lab to lab. The important thing to remember is that, like golf scores, the lower the A1c the better.

Many patients with diabetes get confused about how the A1c value compares to the results they obtain from their finger stick blood sugar. Although this assay value may vary a bit from lab to lab, an A1c value of 7.0 percent represents an average blood sugar of about 170 mg/dl. An A1c value of 9 percent represents an average blood sugar of 240 mg/dl. Values can soar as high as 15 to 20 percent. If you have an A1c value in the double digits you need to make significant lifestyle changes and consult your doctor about a new treatment plan.

The American Diabetes Association recommends the A1c level be below 7.0 and other professional groups such as the American College of Endocrinologists prefer an A1c value lower than 6.5. A1c target values for children tend to be a little higher.

The absolute risk of end-stage microvascular complications (eye disease, kidney disease and amputation) developing over an immediate time frame (6 to 10 years) is low with an A1c of 7.0 or less, at least in patients with no or early complications. However, there is no threshold or lower limit of A1c level at which below such an A1c level complications do not develop, thus the rationale for considering lower A1c target levels. It remains unclear what the absolute benefits and risks are of efforts to achieve A1c targets significantly below A1c levels of 7.0 and decisions to pursue such levels must be individualized between you and your doctor. The U.K. Prospective Diabetes Study (UKPDS) and the Steno-2 Study demonstrated that more intensive blood pressure, lipid and glycemic management together resulted in a substantial reduction in both microvascular (small blood vessel) and macrovascular (large blood vessel) complications. The Diabetes Control and Complications Trial (DCCT) revealed a linear relationship between the HbA1c (glycosylated hemoglobin) values between 8.0% and 5.0% to the risk of eye disease. The study proved that for every 10% decrease in the A1c the risk of developing diabetic retinopathy decreases by 43%.

Patients with diabetes should know their A1c values and be aware of what it means. The A1c value is as much a barometer of your blood sugars as the snap shot value of each finger stick.