Glycosylated Hemoglobin (HbA1C), EDTA Whole Blood

The HbA1c test is a screening test for the diagnosis of diabetes and prediabetes. Hemoglobin A1c is also called as glycated hemoglobin or A1c. HbA1c is formed when glucose attaches to hemoglobin. The amount of glycated hemoglobin formed is directly proportional to the concentration of glucose in the blood. The HbA1c blood test should not be used as a screening test for cystic fibrosis related diabetes, gestational diabetes. The results of HbA1c may not be accurate when there is recent history of severe bleeding or blood transfusions, persons with chronic kidney or liver disease, or people with iron-deficiency anemia, vitamin B12 deficiency anemia, and sickle cell disease or thalassemia, etc. In these cases, a FBS (fasting blood glucose) or oral GTT (glucose tolerance test) should be used for screening or diagnosing diabetes. The A1c test also helps to monitor the control of glucose levels in diabetic patients. Maintaining the glucose levels very close to normal level in diabetic patients helps to reduce the complications such as progressive damage to vital body organs like the kidneys (diabetic nephropathy), eyes (diabetic retinopathy), cardiovascular system, and nerves (diabetic neuropathy). The glycosylated hemoglobin blood test results give a picture of the average glucose levels in the blood over the last 120 days. This can help diabetics and the treating doctor know if the control of diabetes is successful or needs further adjustments.

1. How is estimated Average Glucose (eAG) calculated using HbA1c?

28.7 X A1c (%) - 46.7 = eAG mg/dL

2. Can blood glucose levels be monitored at home?

Yes. In already diagnosed cases of diabetes, glucose levels can be monitored at home using point-of-care test. But this is not recommended for screening or diagnosing diabetes.

3. Why are A1c and blood glucose values different?

HbA1c and blood glucose levels have different units. HbA1c gives an average value of glucose levels over a period of time (120 days) where as blood glucose levels capture the changes that occur on a daily basis.

4. How can blood glucose levels be controlled?

Dietary modifications, regular excercise, life style changes and regular use of medications can control glucose levels.