Facts About A1cMonday, July 21, 2014
What is A1c? Do you measure it with a blood test? What do the results mean? What A1c levels are used to diagnose diabetes and pre-diabetes? What values are considered normal? How often should A1c be tested? These are some of the questions that are asked to our staff at diabetescare.net. Let’s make the answers accessible to everyone that wants to know but did not ask.
What are other names for A1c?
A1c is another name for glucosylated hemoglobin (other names include: hemoglobin A1c, glycated hemoglobin, HbA1c, and A1C).
What is hemoglobin?
Hemoglobin is a protein found in red blood cells. In fact, each red blood cell encloses over 600 million hemoglobin molecules. (1) Hemoglobin is synthesized as red blood cells are made in our bone marrow. (2) Oxygen combines with hemoglobin in our lungs and a substance known as oxyhemoglobin is made. This substance’s function is to carry the oxygen to all tissues using the arteries. After the oxygen is released into our tissues, it is called deoxyhemoglobin and returns to our lungs using our veins and combines with more oxygen.
What is hemoglobin A1C?
Hemoglobin survives in the body for a period of 2-4 months or approximately 60-120 days before it is destroyed in the liver, bone marrow, or spleen. (3) Over the course of its existence, glucose attaches to the hemoglobin. When the blood glucose or sugar is high more glucose will attach to hemoglobin which results in a higher hemoglobin A1c level. Higher blood glucose levels over the past 45-60 days affect the A1c values to a greater extent than for the entire period of 120 days. (4)
Is the A1c a blood test?
Yes it is. The blood is sometime taken through a finger prick and sometimes ordered as lab work and drawn through a vein. The person going for this blood test does not need to fast.
What is A1c used for?
Testing the A1c levels of the blood is considered a very convenient method to detect diabetes mellitus (both type 1 and type 2). (5) Remember, the higher the blood glucose the higher the A1c.
Diagnosing Diabetes and Pre-diabetes with A1c
The A1c test is calculated in percentages. It is a measurement of the percentage of hemoglobin A that has glucose attached to it. The American Diabetes Association uses the following values for diagnosis:
|Normal||less than 5.7%|
|Prediabetes||5.7% to 6.4%|
|Diabetes||6.5% or higher (6)|
Is the A1c test a reliable way to test for diabetes in all adults and children?
Some people have variants in their hemoglobin. The National Glycohemoglobin Standardization Program (NGSP) has a chart with twenty different methods used to test A1c and potential interferences. Click here to see the chart: http://www.ngsp.org/interf.asp Other interferences may occur if a blood transfusion took place in the individual or with loss of blood in the past 3 months and in individuals that have smoked in the past 10-12 hours. (7) You should also tell your doctor if you are pregnant. A1c is sometimes used in early pregnancy but other methods may be preferred later on. Make sure you alert your physician to potential interferences so other methods may be used to test for diabetes.
If I have diabetes, what A1c levels do experts say I should to strive to achieve?
1. Children under the age of 19 with type 1 diabetes have new recommendations by the American Diabetes Association. The new goal is to maintain an A1c level lower than 7.5 percent. This needs to be individualized to the patient. Previously targets of below 8.5 percent were used for young children (under the age of 6 years). Targets were decreased as the child aged and in adolescence they were less than 7.5 percent. The new recommendations are to help avoid serious complications of high blood glucose including kidney disease. (8)
2. Non-Pregnant Adults with diabetes: Recommendations by expert committees recommend A1c values of 7 percent or lower to reduce complications of diabetes and in patients without significant hypoglycemia. When patients have many problems with hypoglycemia, limited life expectancy or advanced complications, a physician may recommend a goal of 8 percent or higher. (9)
How often should a person with diabetes have their A1c tested?
The American Diabetes Association recommends at least twice a year in people that control their blood glucose to their goals and four times a year for those not meeting goals or who have had therapy changes. This is because A1c is strongly correlated to complications of diabetes. (9)
If you have not had your A1c tested and you have diabetes, ask your physician about it. Ask how often you should be tested and as an educated patient, know what your values should be.