Diagnosis and Management of Diabetes

Diagnostic Criteria

The American Diabetes Association recommends using Hemoglobin A1c (HbA1c) as the primary diagnostic test for diabetes and prediabetes, with values ≥6.5% indicating diabetes and 5.7-6.4% indicating prediabetes or high risk of developing diabetes 1, 2
HbA1c levels can be used to diagnose diabetes, with a threshold of ≥6.5% (≥48 mmol/mol) 2
Prediabetes or high risk of developing diabetes is indicated by HbA1c levels of 5.7-6.4% (39-46 mmol/mol) 2

HbA1c reflects average glucose levels over the past 60-90 days, providing a more stable measure of glycemic control than glucose tests 1
HbA1c testing offers technical advantages, including greater preanalytical stability and lower biological variability 1
HbA1c testing does not require fasting or glucose loading, increasing clinical convenience and patient adherence 1

Only NGSP-certified methods should be used in accredited laboratories 1, 2
For diagnosis, a second HbA1c test on a different sample or a glucose-based test is recommended for confirmation 1

Once diabetes is diagnosed, HbA1c should be measured routinely (every 3 months until acceptable targets are reached, then at least every 6 months) 2, 4
Treatment targets should be based on the American Diabetes Association's recommendations, including maintaining HbA1c levels <7% for most people with diabetes 2
More stringent targets (<6.5%) may be appropriate for selected patients with short duration of diabetes, lifestyle treatment or metformin, long life expectancy, or no cardiovascular disease 4