What does an A1c (hemoglobin A1c) level of 6.6 indicate about glucose levels?

Understanding an A1c of 6.6%

An A1c of 6.6% indicates that your average blood glucose level over the past 2-3 months has been approximately 143 mg/dL (7.9 mmol/L), which meets the diagnostic criteria for diabetes mellitus.

A1c and Average Blood Glucose Correlation

According to the American Diabetes Association's standards of care, A1c values directly correlate with estimated average glucose (eAG) levels. The relationship can be understood through this conversion:

• A1c of 6.0% corresponds to an eAG of approximately 126 mg/dL (7.0 mmol/L) 1
• A1c of 7.0% corresponds to an eAG of approximately 154 mg/dL (8.6 mmol/L) 1

Therefore, an A1c of 6.6% falls between these values, indicating an average blood glucose of about 143 mg/dL (7.9 mmol/L) over the previous 2-3 months.

Diagnostic Significance

This A1c value has important clinical implications:

• Diabetes diagnosis: An A1c ≥6.5% meets the diagnostic criteria for diabetes mellitus 1
• Your value of 6.6% exceeds this threshold, indicating diabetes
• This diagnosis requires confirmation with a second test unless you have classic symptoms of hyperglycemia 1

Clinical Context

Understanding what this A1c means for your health:

• Disease progression: This level indicates that your blood glucose has been elevated beyond normal ranges consistently over the past 2-3 months
• Risk assessment: At this level, you have significantly increased risk for diabetes complications including cardiovascular disease, neuropathy, nephropathy, and retinopathy 1
• Monitoring implications: With an A1c of 6.6%, quarterly A1c testing is recommended to monitor response to treatment 1

Limitations to Consider

Several factors can affect A1c results:

• Hemoglobin variants: Certain hemoglobinopathies can interfere with A1c measurement 1
• Ethnic variations: African Americans may have higher A1c levels than non-Hispanic whites with similar glucose levels 1
• Red blood cell turnover: Conditions affecting red blood cell lifespan (anemias, recent transfusions, pregnancy) can alter A1c values 1

Next Steps

With an A1c of 6.6%:

1. Confirm the diagnosis with a second test if this is a new finding
2. Begin appropriate diabetes management strategies
3. Set target A1c goals based on individual factors
4. Schedule follow-up testing in approximately 3 months

Remember that A1c is just one measure of glycemic control. For comprehensive diabetes management, your healthcare provider may also recommend blood glucose monitoring to assess day-to-day glucose levels and glycemic variability.