Table 3

A1C for the diagnosis of diabetes

 • Subject need not be fasting
 • Samples may be obtained any time of the day
 • Very little biological variability
 • Sample stable
 • Not altered by acute factors, e.g., stress, exercise
 • Reflects long-term blood glucose concentration
 • Assay standardized across instruments
 • Accuracy of the test is monitored
 • Single sample, namely whole blood
 • Concentration predicts the development of microvascular complications of diabetes
 • Used to guide treatment
 • May be altered by factors other than glucose, e.g., change in erythrocyte life span, ethnicity
 • Some conditions interfere with measurement, e.g., selected hemoglobinopathies
 • May not be available in some laboratories/areas of the world
 • Cost