What Is HbA1c in a Blood Test?

HbA1c (glycated hemoglobin) measures the percentage of hemoglobin with glucose attached. Reflects average glucose over 2–3 months.

Reference Ranges

• Normal: below 5.7%
• Prediabetes: 5.7–6.4%
• Diabetes: 6.5%+
• Goal for diabetics: below 7.0%
• HbA1c 7% ≈ avg glucose 154 mg/dL
• HbA1c 9% ≈ avg glucose 212 mg/dL

Why HbA1c Is the Gold Standard

• No fasting required
• Not affected by recent meals or stress
• Correlates with complication risk
• Standardized and reliable

Limitations

• Anemia — can falsely alter HbA1c
• Hemoglobinopathies — sickle cell, thalassemia
• Pregnancy — less reliable
• Kidney disease

Testing Frequency

• Screening: every 3 years from age 35
• Prediabetes: annually
• Diabetes (stable): every 6 months
• Diabetes (uncontrolled): every 3 months