What does an Hemoglobin A1c (Hgb A1c) level of 4.7 indicate?

Interpretation of Hemoglobin A1c Level of 4.7%

An HbA1c level of 4.7% indicates a normal glycemic status, well below the diagnostic threshold for both diabetes (≥6.5%) and prediabetes (5.7-6.4%), and represents excellent glycemic control with an estimated average glucose of approximately 88 mg/dL. 1

Understanding HbA1c Values

• HbA1c reflects time-averaged blood glucose during the previous 2-3 months and is used as the gold standard for long-term assessment of glycemic control 1
• According to the American Diabetes Association (ADA) guidelines, HbA1c values correlate with mean glucose levels as follows:
  • HbA1c 5% ≈ 97 mg/dL (76-120 mg/dL)
  • HbA1c 6% ≈ 126 mg/dL (100-152 mg/dL) 1
• By extrapolation, an HbA1c of 4.7% would correspond to an estimated average glucose of approximately 88 mg/dL, which is within the normal non-diabetic range 1

Diagnostic Thresholds

• The diagnostic criteria established by the ADA define:
  • Diabetes: HbA1c ≥ 6.5% (48 mmol/mol)
  • Prediabetes: HbA1c 5.7-6.4% (39-47 mmol/mol)
  • Normal: HbA1c < 5.7% (< 39 mmol/mol) 1
• An HbA1c of 4.7% falls well within the normal range, indicating no evidence of diabetes or prediabetes 1

Clinical Implications

• This HbA1c value suggests excellent glycemic control if the patient is already diagnosed with diabetes and on treatment 1
• In a non-diabetic individual, this value represents normal physiological glucose regulation 1
• The American College of Physicians (ACP) recommends that HbA1c targets should be individualized, with a general target between 7-8% for most patients with type 2 diabetes 1
• An HbA1c of 4.7% may potentially indicate:
  • Normal glucose metabolism in a healthy individual 1
  • Excellent glycemic control in a treated diabetic patient 1
  • Possible falsely low reading in certain clinical conditions 1

Important Considerations

• Falsely low HbA1c values can occur in conditions affecting red blood cell turnover, including:
  • Hemolytic anemia
  • Recent blood transfusion
  • Hemoglobinopathies (e.g., sickle cell trait)
  • Iron deficiency anemia (can cause falsely high or low readings)
  • Pregnancy (second and third trimesters)
  • Erythropoietin therapy
  • End-stage kidney disease 1, 2
• Certain hemoglobin variants can interfere with HbA1c measurement, potentially causing discrepancies between measured HbA1c and actual glycemic status 1
• African American individuals with the common hemoglobin variant HbS may have lower A1C by about 0.3% compared to those without the trait for the same level of mean glycemia 1

Recommendations

• For a patient with an HbA1c of 4.7%:
  • If not diabetic: Reassure that glycemic status is normal 1
  • If diabetic on medication: Evaluate for possible hypoglycemia risk, especially if on insulin or sulfonylureas 1
  • Consider checking for conditions that might cause falsely low HbA1c readings if clinical presentation doesn't match this value 1, 2
• Ensure the HbA1c test was performed using a method certified by the National Glycohemoglobin Standardization Program (NGSP) and standardized to the Diabetes Control and Complications Trial (DCCT) assay 1
• If there is marked discrepancy between measured HbA1c and plasma glucose levels, consider using alternative methods for assessing glycemic status 1