HbA1c (Hemoglobin A1c)
A blood test that reflects average blood glucose over about the past three months by measuring glucose attached to hemoglobin.
Plain English
HbA1c is a longer-term blood sugar average.
Why It Matters After 40
It gives a broader view than one fasting glucose result, but it can hide spikes, lows, and daily variability.
What To Do With It
Use HbA1c with symptoms, medication context, and when available, CGM metrics like time in range.
Human Utility
- Know what the term means before uploading data into an AI tool.
- Separate explanation from medical interpretation.
- Bring trend data and context to the appointment instead of one isolated number.
Proof Structure
It reflects about three months
NIDDK describes the A1C test as a blood test that provides information about average blood glucose over the past three months.
Source: NIDDK A1C test