What is an A1C test?

The A1C (hemoglobin A1C or HbA1c) measures your average blood sugar over roughly the past three months - it works because sugar in your bloodstream sticks to hemoglobin in red blood cells, and red cells live about that long, so the percentage coated is a running average no single-day reading can fake, per MedlinePlus. Its two jobs: diagnosing and tracking. For diagnosing, it is the standard test for prediabetes and diabetes - higher percentages mean higher average sugar, with the lines at 5.7 percent (prediabetes begins) and 6.5 percent (diabetes territory) - and unlike a fasting glucose it needs no fasting: eat normally, any hour of day. For tracking, it is the scoreboard of diabetes management: the quarterly or twice-yearly check that shows whether the medication, food, and activity plan is actually working. Its blind spots are worth knowing: anything that changes red-cell lifespan skews it (some anemias, recent blood loss), a single day's behavior barely moves it (that is the point - it resists gaming), and it reports an average, so wild daily swings can hide inside a decent number. If your result lands near a boundary, expect a repeat or a second type of test to confirm - one number rarely seals a diagnosis alone. Pymander is a free AI doctor, 24/7 by text, that can help you read your result in context.