A1C to Blood Sugar

Average blood glucose over 2–3 months. Red blood cells carry glucose-attached hemoglobin; the ratio reflects long-term average. More reliable than single glucose reading.

< 5.7% = normal; 5.7–6.4% = prediabetic; ≥ 6.5% = diabetic. Goal for most diabetics: < 7% (some target < 6.5%). Individual targets vary by age/comorbidities.

Non-diabetic: baseline only. Prediabetic: annually. Diabetic: 2–4 times/year depending on control. More frequent if changing treatment or poorly controlled.