Hemoglobin A1c is a measure of how healthy average blood sugar levels have been in the recent few months, and is a better representation of blood sugar resilience than a single glucose measurement, since glucose levels vary throughout the day. HbA1c forms in the blood when a hemoglobin molecule in a red blood cell binds with a glucose molecule in the blood; the resulting molecule is also known as glycated hemoglobin (sugar coated or damaged red blood cells).