Do we perform a Hemoglobin A1c (HbA1c) test on a 22-year-old female with a Body Mass Index (BMI) of 36?

HbA1c Testing in a 22-Year-Old Female with BMI of 36

Yes, HbA1c testing is recommended for this 22-year-old female with a BMI of 36 as she meets the criteria for diabetes screening due to her obesity risk factor. 1, 2

Rationale for Testing

The American Diabetes Association (ADA) guidelines provide clear recommendations for diabetes screening in individuals with risk factors:

• BMI ≥25 kg/m² is considered a significant risk factor for diabetes 1
• This patient has a BMI of 36, which falls into the obesity category and significantly increases her diabetes risk
• Obesity is an independent indication for diabetes screening regardless of age 2

Testing Approach

Recommended Test

• HbA1c is appropriate for initial screening as it:
  • Does not require fasting
  • Reflects average glycemia over the preceding 2-3 months
  • Has greater preanalytical stability than plasma glucose measurements 1
  • Should be performed using a method that is NGSP certified and standardized to the DCCT assay 1

Interpretation of Results

• Normal: <5.7%
• Prediabetes: 5.7-6.4%
• Diabetes: ≥6.5% 2

Confirmatory Testing

• In the absence of unequivocal hyperglycemia, diagnosis requires:
  • Two abnormal test results from the same sample (e.g., both FPG and HbA1c)
  • OR two abnormal results from samples obtained on different days 1

Important Considerations

Potential Limitations of HbA1c

• HbA1c may not accurately reflect glycemia in conditions affecting red blood cell turnover:

  • Hemoglobinopathies
  • Pregnancy (second and third trimesters)
  • Recent blood loss or transfusion
  • Erythropoietin therapy 1

• If there's marked discrepancy between measured HbA1c and plasma glucose levels, consider:

  • Possible HbA1c assay interference
  • Using an assay without interference
  • Using plasma blood glucose criteria instead 1

Alternative Testing Options

If HbA1c is not appropriate or available:

• Fasting plasma glucose (FPG ≥126 mg/dL indicates diabetes)
• 2-hour plasma glucose during OGTT (≥200 mg/dL indicates diabetes) 1

Follow-up Testing

If initial results are normal:

• Repeat testing every 3 years 2

If prediabetes is diagnosed:

• Annual testing is recommended 1, 2

If diabetes is diagnosed:

• Test HbA1c at least twice per year in patients meeting treatment goals
• Test quarterly in patients whose therapy has changed or who are not meeting glycemic goals 1

Clinical Pearls

• Young adults with obesity are at increased risk for early-onset type 2 diabetes
• Early detection of prediabetes allows for lifestyle interventions that may prevent or delay progression to diabetes
• Point-of-care A1c testing should not be used for diagnosis unless FDA-cleared for this purpose 1
• The relationship between HbA1c and mean glucose can vary between individuals, so clinical context is important when interpreting results 3