What is consistent with a diagnosis of diabetes according to the American Diabetes Association (ADA) criteria?

Diagnostic Criteria for Diabetes According to the American Diabetes Association

According to the American Diabetes Association (ADA), a hemoglobin A1C level of 6.5% or greater is diagnostic of diabetes mellitus. 1, 2

ADA Diagnostic Criteria for Diabetes

The ADA has established four primary methods for diagnosing diabetes:

• A1C ≥ 6.5% (when performed in a laboratory using a method that is NGSP certified and standardized to the DCCT assay) 1, 2
• Fasting plasma glucose (FPG) ≥ 126 mg/dL (7.0 mmol/L) after at least 8 hours of fasting 1
• 2-hour plasma glucose ≥ 200 mg/dL (11.1 mmol/L) during an oral glucose tolerance test (OGTT) using a 75-g glucose load 1
• Random plasma glucose ≥ 200 mg/dL (11.1 mmol/L) in a patient with classic symptoms of hyperglycemia or hyperglycemic crisis 1, 2

Confirmation Requirements

• In the absence of unequivocal hyperglycemia with acute metabolic decompensation, these criteria should be confirmed by repeat testing 1
• Confirmation can be accomplished by:
  • Repeating the same test on a different day 1
  • Using a different test (e.g., if A1C was initially used, FPG can be used for confirmation) 1
  • Measuring two different tests (glucose and A1C) on the same day 1

Special Considerations for A1C Testing

• A1C testing for diagnosis should be performed in a laboratory using a method that is NGSP certified and standardized to the DCCT assay 1
• Point-of-care A1C assays should not be used for diagnostic purposes due to lack of standardization 1
• A1C may be affected by:
  • Hemoglobinopathies
  • Certain anemias
  • Conditions with abnormal red blood cell turnover 2
• In cases where A1C cannot be reliably measured, glucose criteria should be used exclusively for diagnosis 2

Categories of Increased Risk for Diabetes (Prediabetes)

• A1C: 5.7-6.4% 1
• Fasting glucose: 100-125 mg/dL (5.6-6.9 mmol/L) (impaired fasting glucose) 1
• 2-hour OGTT: 140-199 mg/dL (7.8-11.0 mmol/L) (impaired glucose tolerance) 1

Clinical Implications

• Early diagnosis of diabetes is crucial as it allows for timely intervention to prevent or delay complications 1
• Patients meeting criteria for prediabetes should be counseled on effective strategies to lower their risk of progression to diabetes, such as weight loss and exercise 1
• The diagnostic criteria for diabetes are based on the threshold at which the risk of microvascular complications (particularly retinopathy) increases substantially 1

Diagnostic Approach in Special Populations

• Pregnancy: Women with risk factors should be tested for undiagnosed type 2 diabetes at the first prenatal visit using standard diagnostic criteria 1
• Gestational diabetes: Testing should be done at 24-28 weeks of gestation using either the "one-step" 75-g OGTT or the "two-step" approach 1
• Children: All children diagnosed with diabetes in the first 6 months of life should have genetic testing 1

Remember that proper diagnosis of diabetes is essential for appropriate management and prevention of complications that affect morbidity, mortality, and quality of life.