Hemoglobin A1C (HgbA1c) has typically been reported as a %. This is the unit we use for both CU and SI in Optimal. So, ALL results for HgbA1c in the Optimal database are in the % unit. It has become more common in countries using SI units to report HgbA1c in a unit called mmol/ml.

The 2 units are governed by 2 different entities:

• The NGSP Network governs the HgbA1c%
• The IFCC Network governs HgbA1c in mmol/L