Does an A1c of 5.6% Mean You're Prediabetic?
No, an A1c of 5.6% does not meet the diagnostic threshold for prediabetes according to current American Diabetes Association guidelines—prediabetes is defined as A1c 5.7–6.4%. 1
Understanding the Threshold
The most recent 2025 ADA Standards of Care clearly define prediabetes as:
- A1c range: 5.7–6.4% (39–47 mmol/mol) 1
- This threshold is consistent across the 2023 and 2025 guidelines 1, 2
Your A1c of 5.6% falls just below this cutoff, placing you technically in the normal range.
Important Clinical Context
However, risk exists on a continuum—it doesn't suddenly appear at 5.7%. The guidelines explicitly note that "for all three tests, risk is continuous, extending below the lower limit of the range" 2. This means:
- An A1c between 5.5–6.0% carries a substantially increased diabetes risk (5-year incidence 9–25%) 2
- An A1c of 5.6% represents borderline elevation and warrants attention
- You are at the upper edge of normal, approaching the prediabetes threshold
What You Should Do
At A1c 5.6%, you should:
- Assess your risk factors for diabetes (see below)
- Implement lifestyle modifications now—don't wait until you cross 5.7%
- Retest in 1 year if you have risk factors, or every 3 years if low risk 1
Key Risk Factors to Evaluate:
- Overweight/obesity (BMI ≥25 kg/m², or ≥23 kg/m² if Asian)
- First-degree relative with diabetes
- High-risk ethnicity (African American, Latino, Native American, Asian American)
- Hypertension (≥130/80 mmHg)
- Physical inactivity
- History of cardiovascular disease
- HDL <35 mg/dL or triglycerides >250 mg/dL
- Polycystic ovary syndrome
- History of gestational diabetes 1
Clinical Nuances
The 5.7% threshold is somewhat arbitrary. Research shows:
- Some studies suggest 5.6% as an optimal cutoff in certain populations 3, 4
- The threshold may vary by ethnicity and BMI—obese individuals may need higher cutoffs (up to 6.0%) for equivalent risk 4
- One study found A1c <5.6% had 100% negative predictive value to exclude prediabetes/diabetes 5
Recent evidence (2026) supports a tiered approach: 6
- A1c 5.7–6.4% for broad, low-intensity preventive advice
- A1c 6.0–6.4% for structured prevention programs and closer follow-up
- This reflects that risk is graded, not binary
Bottom Line
While you don't technically have prediabetes at 5.6%, you're in a gray zone that deserves proactive management. The difference between 5.6% and 5.7% is clinically negligible—both indicate elevated risk compared to someone with A1c <5.5%. Focus on modifiable risk factors (weight, diet, exercise) rather than fixating on whether you've crossed an arbitrary diagnostic line. If you have multiple risk factors listed above, treat yourself as if you're in the prediabetes range and pursue intensive lifestyle modification now.