A. The hemoglobin A1c test, also called HbA1c, glycated hemoglobin test, or glycohemoglobin, is an important blood test that shows how well your diabetes is being controlled.hen your diabetes is not controlled (meaning that your blood sugar is too high), sugar builds up in your blood and combines with your hemoglobin, becoming glycated.. The average amount of sugar in your blood can be found by measuring your hemoglobin A1c level.