Hemoglobin (Hb) A_1c

Whole blood

4 mL

Pediatric EDTA whole blood tubes may be used. Please place original labeled capillary tube in a labeled transport tube for shipment to the laboratory. (Note: This volume does not allow for repeat testing.)

Lavender-top (EDTA) tube, green-top (lithium heparin) tube, or gray-top (sodium fluoride) tube

Hemoglobin A_1c values are used to assess glucose control in diabetes, and in 2010 the American Diabetes Associations affirmed the decision of an international expert committee recommendation to use the A_1c test to diagnose diabetes with a threshold ≥6.5%. Point-of-care A_1c assays are not sufficiently accurate at this time to use for diagnostic purposes.

Any cause of shortened erythrocyte survival will reduce exposure of erythrocytes to glucose with a consequent decrease in Hb A_1c (%). Causes of shortened erythrocyte lifetime might be hemolytic anemia or other hemolytic diseases, homozygous sickle cell trait, pregnancy, or recent significant or chronic blood loss. Glycated Hb F (fetal hemoglobin) is not detected as it does not contain the glycated β chain that characterizes Hb A_1c. Specimens containing high amounts of Hb F (>10%) may result in lower than expected Hb A_1c.

Roche Tina Quant

• Hemoglobin (Hb) A_1c: 4.8% to 5.6%

• Prediabetes: 5.7% to 6.4%

• Diabetes: ≥6.5%

• Glycemic control for adults with diabetes: <7.0%

(DCCT/NGSP)

2010 American Diabetes Association's Summary of Glycemic Recommendations for Adults with Diabetes: Hemoglobin A_1c <7.0%.

For selected individual patients, providers might reasonably suggest even lower A_1c goals than the general goal of <7%, if this can be achieved without significant hypoglycemia or other adverse effects of treatment. Such patients might include those with short duration of diabetes, long life expectancy, and no significant CVD. Conversely, less-stringent A_1c goals than the general goal of <7% may be appropriate for patients with a history of severe hypoglycemia, limited life expectancy, advanced microvascular or macrovascular complications, and extensive comorbid conditions and those with longstanding diabetes in whom the general goal is difficult to attain.

Factors such as duration of diabetes, adherence to therapy, and age of patient should also be considered in assessing the degree of blood glucose control.