Hemoglobin A1c (HbA1c)
What it measures
HbA1c reflects average blood sugar over the prior 3 months by measuring the percentage of hemoglobin with glucose attached. It's the standard test for diagnosing and monitoring diabetes.
When it’s ordered
Diabetes diagnosis (≥6.5% confirms), monitoring known diabetes (target typically <7.0%), pre-diabetes screening (5.7–6.4%).
Medicare coverage
Governed by NCD 190.21. Frequency limit is typically 4× per year for known diabetes, less often for screening. R73.x (hyperglycemia / abnormal glucose) and E11.x (Type 2 diabetes) codes are widely accepted.
Typical price
Medicare allowable around $9–13. Commercial cash prices range from $20 to $120.