A1C (HbA1c)
A blood test estimating your average glucose over the past two to three months.
A1C measures the share of hemoglobin in your red blood cells that has glucose attached. Because those cells live about three months, it reflects your average glucose over that window: a single number that smooths out daily ups and downs.
General reference points: below 5.7% is typical, 5.7–6.4% suggests prediabetes, and 6.5% or above is in the diabetes range. Your own targets are a conversation for you and your clinician.