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Hemoglobin A1c (HbA1c) from whole blood

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

This test measures the average level of hemoglobin A1c in your blood over the past 2–3 months, reflecting your long-term blood sugar control.

Quick summary

["HbA1c helps doctors track diabetes management and identify trends in blood sugar levels."]

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

Key facts at a glance

LOINC
4619-3
Short code
Hgb Ranier Bld Ql
Synonyms
Hgb Ranier Bld Ql
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 This Test Matters

HbA1c is a key indicator of how well your body manages blood sugar over time. Unlike daily blood glucose checks, it provides a snapshot of your average glucose levels, helping prevent complications like nerve damage, kidney disease, or heart problems.

How It Works

Blood is drawn from a vein, usually in your arm. The test measures the percentage of hemoglobin molecules that are coated with glucose, reflecting your average blood sugar levels from the past 2–3 months.

What It Measures

HbA1c is a form of hemoglobin (the protein in red blood cells that carries oxygen) that has attached glucose molecules. It’s stable in blood and doesn’t change until red blood cells are destroyed, giving it a long-term perspective on blood sugar.

Common Uses

Doctors use HbA1c to diagnose diabetes, monitor treatment progress, and adjust medications if needed. It’s also useful for people with prediabetes to assess risk and those with diabetes to ensure their blood sugar stays within healthy ranges.

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 HbA1c result above the typical range (usually 4–6% for non-diabetics, higher for those with diabetes) may indicate poor blood sugar control, which can increase the risk of diabetes-related complications. Your doctor will discuss results in the context of your overall health and treatment plan.
How often should I get this test?
If you have diabetes, your doctor may recommend checking HbA1c every 3–6 months to track progress. For prediabetes or healthy individuals, testing may be less frequent unless advised otherwise.
Does diet or exercise affect HbA1c results?
Yes! While HbA1c reflects long-term trends, lifestyle changes like diet, exercise, and medication can influence future results. Consistently managing blood sugar through healthy habits can improve your HbA1c over time.
  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