You may be getting to know the folks at the local lab on a first-name basis, since your doctor will likely want you to come in every few months for a procedure called an A1c test. (At-home versions of the test are now available, too.)

As you know, when you breathe, your lungs take in oxygen. The lungs, in turn, hand over oxygen molecules to red blood cells. Like tiny FedEx trucks, red blood cells deliver oxygen to cells in every tissue in your body, which need the Big O to produce energy. Each of those little couriers has a special compartment for carrying oxygen, a protein called hemoglobin.

Glucose molecules love attaching themselves to proteins (a process called glycation), and hemoglobin is no exception. When glucose and hemoglobin hook up, the result is glycated hemoglobin or glycohemoglobin. The more glucose you have in your blood, the more glycated hemoglobin you will have. The A1c test measures glycated hemoglobin. This test is sometimes called a hemoglobin A1c or HbA1c test. There are several different types of glycated hemoglobin; the type named A1c just happens to be the easiest to measure and least likely to be influenced by what you ate the night before.

©2007 Publications International, Ltd. Most experts recommend that diabetics have an A1c test at least twice a year.

But why measure this little sugar-protein package at all when it's easy enough just to measure blood sugar, period? The blood-sugar testing you do at home offers a snapshot of how well you are controlling glucose at that very moment. The A1c test, meanwhile, is more like a chronicle or history, giving your doctor a look at how well you have been controlling glucose on average in recent months.

Neat trick, no? But how the heck does it do that? Red blood cells have a shelf life of about two or three months, so your body is constantly churning out new ones, while others are dying off. At any given time, you have red blood cells on the job that are brand new, others that have been around for a few days or weeks, and still others that are ready to call it quits. Once the hemoglobin in a red blood cell links to a glucose molecule, it stays that way. The A1c test measures young, middle-aged, and old hemoglobin, indicating what percent has been carrying sugar over the last few months.

Most experts suggest having an A1c test at least twice a year. It's also a good idea to have the test before starting on a new medication, then following up in a few months to see how well it's controlling blood sugar. Don't toss out your glucose meter and logbook, though. You still need to take daily readings for status updates on your blood sugar. And your logbook not only provides information about daily fluctuations in your glucose levels, but comparing the results of an A1c test with the averages you compile on your own over time can tell you whether or not your glucose meter is providing accurate readings.

People who don't have diabetes usually have about five percent of hemoglobin that's glycated. In a person with runaway, out-of-control diabetes, the figure can rise to more than 20 percent. You want to keep yours as close to normal as possible, of course, in order to avoid the complications that high blood sugar can cause over the long term. The American Diabetes Association recommends an A1c goal of less than seven percent, though your doctor owes you a high-five if you can keep it even lower.

For more information on blood sugar and diabetes, try the following links:

• Read Blood Sugar for valuable information about blood glucose and its link to diabetes.
• How to Test Blood Sugar will show you how to test your glucose levels accurately.
• To learn why it is important for you to test your glucose levels, read Benefits of Monitoring Blood Sugar.
• For more information on the machines that test you blood sugar, read Glucose Meters.
• To learn more about diabetes in general, including diagnosis, causes, symptoms, and treatment, visit our main Diabetes page.
• For a description of treatment options for diabetics, read Diabetes Treatment.

ABOUT THE AUTHOR:

Timothy Gower is a freelance writer and the author of several books. His work has appeared in many magazines and newspapers, including Prevention, Health, Reader's Digest, Better Homes and Gardens, Men's Health, Esquire, Fortune, The New York Times, and The Los Angeles Times.

ABOUT THE CONSULTANTS

Dana Armstrong, R.D., C.D.E., received her degree in nutrition and dietetics from the University of California, Davis, and completed her dietetic internship at the University of Nebraska Medical Center in Omaha. She has developed educational programs that have benefited more than 5,000 patients with diabetes. She specializes in and speaks nationally on approaches to disease treatment, specifically diabetes.

Allen Bennett King, M.D., F.A.C.P., F.A.C.E., C.D.E. is the author of more than 50 papers in medical science and speaks nationally on new advances in diabetes. He is an associate clinical professor at the University of California Natividad Medical Center and cofounder and medical director of the Diabetes Care Center in Salinas, California.

This information is solely for informational purposes. IT IS NOT INTENDED TO PROVIDE MEDICAL ADVICE. Neither the Editors of Consumer Guide (R), Publications International, Ltd., the author nor publisher take responsibility for any possible consequences from any treatment, procedure, exercise, dietary modification, action or application of medication which results from reading or following the information contained in this information. The publication of this information does not constitute the practice of medicine, and this information does not replace the advice of your physician or other health care provider. Before undertaking any course of treatment, the reader must seek the advice of their physician or other health care provider.