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Hemoglobin A1c (HbA1c) with mass fraction measurement by high-performance liquid chromatography (HPLC)

Published: August 9, 2026Updated: August 16, 2026

This test measures the percentage of hemoglobin that is bound to glucose over the past 2–3 months, reflecting your average blood sugar levels during that time.

Quick summary

["HbA1c helps track long-term blood sugar control, useful for managing diabetes."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
53223-4
Short code
Hgb G MFr Bld
Synonyms
Hgb G MFr Bld
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
12
Ref high
17.5
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85018
SNOMED
900000000000003004
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why HbA1c Matters for Diabetes Management

HbA1c is a key indicator of how well your diabetes is controlled over time. Unlike daily blood sugar checks, it provides a broader picture of your average glucose levels, helping healthcare providers adjust treatments like medication or diet.

How HbA1c Works

HbA1c forms when glucose attaches to hemoglobin in red blood cells. Since red blood cells live for about 3 months, this test reflects your blood sugar levels from that period. The test is typically done on a small blood sample drawn from your arm.

What HbA1c Results Mean

Results are usually reported as a percentage. While exact ranges vary by lab, higher percentages generally indicate poorer blood sugar control, while lower percentages suggest better control. Your doctor will interpret results in the context of your overall health and treatment plan.

Common Causes of HbA1c Variations

Several factors can influence HbA1c levels, including recent blood sugar fluctuations, anemia, or certain medications. For example, if you recently had a high or low blood sugar spike, your HbA1c might not reflect your typical levels yet.

Reference range

Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A

Specimen: whole-blood

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

HbA1c

Frequently asked questions

What does an abnormal HbA1c result mean?
An abnormal HbA1c result may signal that your blood sugar levels are consistently too high (hyperglycemia) or too low (hypoglycemia) over time. For people with diabetes, high HbA1c levels can increase the risk of long-term complications like nerve damage, kidney disease, or heart problems. For those without diabetes, elevated levels may indicate prediabetes or undiagnosed diabetes.
How often should I get an HbA1c test?
If you have diabetes, your doctor may recommend HbA1c testing every 3–6 months to monitor progress and adjust treatment. If you’re at high risk for diabetes (e.g., due to family history or obesity), your doctor might suggest testing every 1–2 years.
Can HbA1c be affected by recent blood sugar swings?
Yes, HbA1c can take time to reflect recent blood sugar changes because it measures average levels over months. If you’ve had recent extreme swings (e.g., from a hospital stay or illness), your HbA1c may not be accurate yet. Your doctor may recommend retesting later.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy