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Educational Guides
Evidence-based information about A1C testing and interpretation
Understanding A1C Testing
Learn what A1C is, how it's measured, and why it's important for diabetes management
A1C vs Average Glucose
Understand the relationship between A1C and estimated average glucose (eAG)
Factors Affecting A1C
Medical conditions and factors that can affect A1C accuracy
A1C During Pregnancy
Special considerations for A1C testing during pregnancy and gestational diabetes
Quick Reference Guide
Essential A1C information at a glance
ADA Classification Criteria
| Category | A1C % | IFCC (mmol/mol) | eAG (mg/dL) |
|---|---|---|---|
| Normal | <5.7% | <39 | <117 |
| Prediabetes | 5.7-6.4% | 39-47 | 117-137 |
| Diabetes | ≥6.5% | ≥48 | ≥140 |
Target A1C by Population
- • Most adults: <7% (53 mmol/mol)
- • Healthy younger adults: <6.5% (48 mmol/mol) if achievable without hypoglycemia
- • Older adults/comorbidities: <8% (64 mmol/mol)
- • Children: <7.5% (58 mmol/mol)
- • Pregnancy: <6% (42 mmol/mol) if achievable; <6.5% maximum
Testing Frequency
- • Well-controlled diabetes: Twice yearly
- • Treatment changes or not meeting goals: Quarterly
- • Prediabetes screening: Yearly
- • High-risk individuals: Every 1-3 years starting at age 35
Limitations of A1C Testing
Falsely High A1C:
- • Iron deficiency anemia
- • Vitamin B12/folate deficiency
- • Decreased red cell turnover
- • Asplenia
Falsely Low A1C:
- • Hemolytic anemia
- • Recent blood loss
- • Recent transfusion
- • Certain hemoglobinopathies