HbA1c (Hemoglobin A1c)
What This Test Measures
Average blood sugar over 2-3 months; the diagnostic and monitoring standard for diabetes management.
Preparation
IMPORTANT: Iron deficiency falsely ELEVATES HbA1c. If you have low ferritin or iron deficiency anemia, your A1c may overestimate your average blood sugar. This is well-documented in research but rarely mentioned on standard lab reports. The functional medicine community recommends interpreting A1c alongside fasting insulin and fasting glucose — not in isolation. Functional practitioners consider optimal A1c to be 4.6–5.3%, tighter than the standard <5.7% cutoff. Hemoglobin variants (sickle cell trait, thalassemia) can also affect accuracy. No fasting required for this test. These notes reflect common practices in functional medicine communities.
Reflects common practices in thyroid, BHRT, and functional medicine communities. This may differ from standard clinical guidelines. Not medical advice — always discuss with your provider.
General guidelines only. Requirements vary by lab and individual. Confirm with your provider before adjusting any medications.
Turnaround Time
Varies by lab
Clinical Notes
<5.7% normal; 5.7-6.4% prediabetes; >=6.5% diabetes; no fasting required
ICD-10 Codes
Common diagnosis codes associated with this test. Codes are assigned by your provider.
Self-Pay Pricing
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Uses LabCorp draw centers · Not available in NY, NJ, RI, HI, ND, or VT · Membership may be required
Uses both Quest and Labcorp networks; competitive pricing; broad test selection
Uses Quest Diagnostics network; generally lowest DTC prices; not available in NY, NJ, RI
Uses Labcorp network; known for supplement company; competitive lab test pricing
Uses Quest and Labcorp networks; offers both individual tests and discounted panels
Uses Quest Diagnostics network; good panel pricing; established DTC provider
Uses Quest and Labcorp; strong panel bundling; results in 1-3 days
Labcorp consumer-direct platform; 2,000+ locations; results in 1-3 days
Uses Quest and Labcorp; no hidden draw or facility fees; moderate pricing
Quest Diagnostics consumer-direct platform; results in 1-2 days; 2,100+ locations nationwide
Primarily uses Labcorp network; popular for hormone panels; higher individual test prices
At-home self-collection. Finger prick or swab — no lab visit required. Results via secure portal within 10 business days.
Lab Codes
Proprietary codes used by each lab for this test.
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For informational purposes only
This page is for educational and research purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. ICD-10 and CPT codes are assigned by your healthcare provider. Always consult a qualified healthcare provider before ordering any lab test or making decisions about your health.