HbA1C is a retrospective measure of average blood glucose levels over the preceding 2 — 3 months where a higher number represents poorer metabolic control. (academic.oup.com)
A1C readings provide a snapshot of average blood glucose levels over the past two to three months to give an idea of how well diabetes therapy is working. (health.com)
So A1c serves as a biomarker, indicating average blood glucose levels over a two - to three - month period. (sciencedaily.com)