What are the recommendations for a patient with a hemoglobin A1c (HbA1c) result of less than 3.8%?

Recommendations for Hemoglobin A1c Below 3.8%

For a patient with a hemoglobin A1c (HbA1c) result less than 3.8%, repeat testing should be performed within 3 months while investigating potential causes of falsely low values, particularly hemolytic anemia. 1, 2

Understanding Abnormally Low HbA1c Values

• HbA1c values below the reference range (typically 4-6% in non-diabetic individuals) are unusual and warrant investigation 1
• Abnormally low HbA1c values (< 3.8%) often indicate conditions that shorten erythrocyte lifespan rather than reflecting true glycemic status 2
• Common causes include hemolytic anemia, recent blood loss, or other conditions affecting red blood cell turnover 1

Recommended Approach

Immediate Steps:

• Evaluate for symptoms or history of hemolytic anemia (fatigue, jaundice, shortness of breath) 2
• Order additional laboratory tests to assess for hemolysis:
  • Complete blood count with peripheral smear
  • Reticulocyte count
  • Haptoglobin
  • Lactate dehydrogenase
  • Bilirubin (direct and indirect) 2

Follow-up Testing:

• Repeat HbA1c measurement within 3 months 1
• Consider alternative methods of glycemic assessment if hemolysis is confirmed:
  • Fasting plasma glucose
  • Random plasma glucose
  • Continuous glucose monitoring if available 1, 3

Interpretation of HbA1c Results

• The American Diabetes Association recommends HbA1c testing at least twice yearly in patients with stable glycemia and quarterly in patients whose therapy has changed or who are not meeting glycemic goals 3
• HbA1c values must be interpreted in context of conditions affecting erythrocyte turnover 1
• In patients with confirmed hemolytic conditions, HbA1c is considered a poor marker for overall glycemia 2

Clinical Considerations

• Falsely low HbA1c values can mask hyperglycemia, potentially leading to undertreatment of diabetes 2
• In patients with diabetes and hemolytic conditions, more frequent blood glucose monitoring or continuous glucose monitoring may be necessary to guide treatment decisions 3
• Document the suspected cause of low HbA1c in the medical record to prevent misinterpretation of future results 1

Common Pitfalls to Avoid

• Assuming low HbA1c values always represent excellent glycemic control without investigating potential causes of falsely low results 2
• Failing to recognize that conditions affecting red blood cell lifespan invalidate HbA1c as a reliable marker of glycemic control 1, 2
• Overlooking the need for alternative methods of glycemic assessment in patients with conditions that affect HbA1c reliability 3