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Glycated hemoglobin is a form of hemoglobin that is chemically linked to a sugar. Most monosaccharides, including glucose, galactose and fructose, spontaneously bond with hemoglobin, when present in the bloodstream of humans.

Test PurposeThis assay is useful for diagnosing Diabetes and evaluating long term control of blood glucose concentrations in diabetic patients. It reflects the mean glucose concentration over the previous period of 8 to 12 weeks and is a better indicator of long term glycemic control as compared with blood glucose levels due to lesser day to day variation.
Pretest PreparationsNo special preparation required
Specimen3 mL (2 mL min.) whole blood in 1 Lavender Top (EDTA) tube. Ship refrigerated. DO NOT FREEZE.
Stability Room6 hrs
Stability Refrigerated1 week
Stability FrozenNA
MethodHigh Performance Liquid Chromatography, NGSP certified

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Also Known as: A1c, HbA1c, Glycohemoglobin, Glycated Hemoglobin, Glycosylated Hemoglobin,Hemoglobin A1C, HgbA1c

Test Purpose:

  1. This test is used to monitor diabetes control.
  2. This test tells us the patient average glucose index over a long period of time (2 to 3 months).
  3. It tracks glucose in the milder form of diabetes.
  4. It helps to determine which type of drugs may be needed.
  5. Its measurement is of value in a specific group of patients like:
    • Diabetic children
    • Diabetic patients whose renal threshold for glucose is abnormal.
    • Unstable diabetes type I, taking insulin.
    • Type II diabetic women who become pregnant.
    • Patients with changing dietary or other habits.
  6. It should be repeated every 3 to 4 months.

Sample Required:

  1. The blood sample is taken in the EDTA 3 to 4 ml.
  2. Washed RBC or hemolysate is prepared and this is stable for 4 to 7 days at 4 °C.
  3. A blood sample can be drawn at any time.


Source 1

  • HbA1 c (% of total Hb) = 4.0 to 5.2
  • Hb A1  (%  of  total Hb) 5.0 to  7.5

Source 2

  1. Non Diabetic adult = 2.2 to 4.8 %.
  2. Non Diabetic child = 1.8 to 4.0 % .
    1. Prediabetic              = 5.7 to 6.4 %
    2. Diabetics                  = >6.5 %
    3. Diabetic HbA1c = > 8.1 % = corresponds with glucose >200 mg/dl.

Diabetic Control And HbA1c

  1. Good diabetic control = 2.5 to 5.9 %.
  2. Fair diabetic control = 6 to 8 %.
  3. Poor diabetic control = > 8 %.
    • (Values may vary according to the lab)

The following table gives a recommendation for the treatment:

HbA1c level mg/dLmmol/LInterpretation
71709.5ADA target
820511.5treatment needed
924013.5treatment needed
1027515.5treatment needed
1126914.9treatment needed
1229816.5treatment needed
1332618.0treatment needed
1435519.7treatment needed
HbA1c And Estimated Blood Glucose Level:
HbA1c levelGlucose level  mg/dL

Formula = mg/dL /18 = mmol/L

                    mmol/L  x 18 = mg/dL

Increased Level Is Seen In:

  1. Newly diagnosed diabetic patient.
  2. Uncontrolled diabetic patient.
  3. Nondiabetic hyperglycemia is seen in:
    1. Cushing’s syndrome.
    2. Acromegaly.
    3. Corticosteroids therapy.
    4. Pheochromocytoma.
    5. Acute stress.
    6. Glucagonoma.
  4. Patient with splenectomy.
  5. Alcohol toxicity.
  6. Iron deficiency anemia.
  7. Lead toxicity.

Decreased HbA1c Level Is Seen In:

  1. Hemolytic anemia.
  2. Chronic blood loss.
  3. Chronic renal failure.
  4. Pregnancy.

Related Articles:

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Keywords: Glycohemoglobin A, Glycosylated Hemoglobin A, Hb A1, Hb A1a+b, Hb A1c, HbA1, Hemoglobin A(1), Hemoglobin A, Glycosylated, Glycosylated hemoglobin A, HBA GLYCOSYLATED, HBA 01, HEMOGLOBIN AA 01, HB AC 01, Haemoglobin A1c, HbA1c, HbA>1c<, Hemoglobin A1c, HbA1c, Hemoglobin A, Glycosylated [Chemical/Ingredient], hemoglobin a1c, hba1, hemoglobin a 1, glycosylated hemoglobin a, hb a1, hba1c, haemoglobin a1c, HbA1c (substance), HbA1c (substance), HbA>1c< (substance), HbA1 – Glycated haemoglobin, HbA1 – Glycated hemoglobin, Glycosylated haemoglobin A, Glycosylated hemoglobin A (substance)

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