A1C measures your average blood sugar level over the last 2–3 months by looking at how much sugar is attached to your red blood cells.

What A1C Actually Measures

  • A1C (also called HbA1c or glycated hemoglobin) measures the percentage of hemoglobin in your red blood cells that has sugar stuck to it.
  • Because red blood cells live about 3 months, that percentage reflects your average blood glucose over the past 2–3 months , not just today’s reading.

In simple terms:

Higher A1C % = your blood has been exposed to higher sugar levels over the past few months.

Why Doctors Care About A1C

  • It’s used to diagnose prediabetes and type 2 diabetes (typical cutoffs: normal below 5.7%, prediabetes 5.7–6.4%, diabetes 6.5% or higher).
  • For people with diabetes, it helps monitor how well blood sugar is controlled over time , beyond day‑to‑day ups and downs.

If you imagine checking your blood sugar with a finger‑stick meter as a “snapshot,” A1C is more like the 3‑month average of all those snapshots combined.

Information gathered from public forums or data available on the internet and portrayed here.