Advantages of utilization of Hb A1C over blood glucose measurement include:
- Fasting is not required.
- Greater specimen stability.
- Less fluctuations in day-to-day levels caused by stress and illness.
Disadvantages of utilization of Hb A1C over blood glucose measurement include:
- Cost per test is higher than blood glucose.
- Conditions that shorten red blood cell (RBC) survival (eg, hemolytic anemia, homozygous sickle cell trait, pregnancy, or recent significant blood loss) will reduce exposure of RBCs to glucose, thereby lowering the Hb A1C test value.
- Specimens with >10% fetal hemoglobin (HbF) may have a falsely decreased Hb A1C test result.
- If onset of diabetes is rapid, blood glucose levels will more correctly reflect glycemia than Hb A1C levels.