Diabetes is a condition in which blood glucose levels are too high due to problems with a hormone called insulin. Patients who do not make enough insulin or who are resistant to its function can develop diabetes. One method of measuring blood glucose levels, known as hemoglobin A1c testing, measures blood glucose levels indirectly.
Hemoglobin A1c
Hemoglobin A1c, according to website Diabetes Monitor, is a specially modified form of the protein hemoglobin, which is used to carry oxygen in the blood to different tissues. Glucose in the bloodstream is able to attach to these hemoglobin molecules via a chemical reaction known as glycosylation. When the sugar attaches to the hemoglobin molecule, it stays attached until the hemoglobin is broken down by the body. The more sugar that is present in the blood, the more hemoglobin A1c is formed. Because hemoglobin molecules last on average for 120 days in the blood, hemoglobin A1c testing can be used to determine a patient's average blood sugar level for the previous four months.
Procedure
The A1c test requires a blood sample; the blood is normally taken from a vein in the back of the hand or the inside of the elbow, notes the New York Times. The testing site will be cleaned with an antiseptic, then an elastic band will be placed near the area to make the vein swell with blood. A needle is then put into the vein and blood is collected into a tube or some other air-tight container. For young children, a special needle, known as a lancet, may be used instead.
Results
Hemoglobin A1c results are reported in terms of the percentage of hemoglobin molecules that have been glycosylated. People without diabetes will have, on average, normal blood glucose levels, which will typically result in hemoglobin A1c levels of between 4 percent and 6 percent. Levels between 5.7 and 6.4 percent, Lab Tests Online notes, are indicative of prediabetes, which is a condition in which patients are not technically diabetic but are at a greater risk of developing diabetes. Anything over 6.5 percent is undesirably high and is typical of a patient with poorly controlled diabetes.
Indications
Hemoglobin A1c testing is typically performed between two and four times a year on patients with diabetes to see how well their disease is controlled. The number of times this test is recommended depends on the type of diabetes, as well as how high the patient's blood glucose numbers have been in the past. Hemoglobin A1c testing can also be used to screen people for diabetes, either at community health fairs or for patients who are suspected of having diabetes.
Importance
One of the advantages of the hemoglobin A1c test is that it measures a patient's average blood glucose level over the course of several months. This means it won't be affected by temporary rises and falls in blood glucose levels that can occur over the course of one or more days. Studies have also found, according to the Diabetes Monitor, that patients with diabetes can benefit greatly from lowering their hemoglobin A1c levels, as lower A1c percentages are associated with a reduced risk of developing complications related to diabetes, such as blindness, heart disease, poor circulation and numbing of the extremities.
