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Glucose (Serum)

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

This test measures the amount of glucose, a type of sugar, in your blood. It helps doctors check how well your body is using food for energy.

Quick summary

["Glucose levels can indicate how your body processes food and may help detect diabetes or other health conditions."]

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

Key facts at a glance

LOINC
18185-9
Short code
GA
Synonyms
GA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order a glucose test to monitor blood sugar levels, especially if you have diabetes, prediabetes, or symptoms like excessive thirst, frequent urination, or unexplained weight changes. It can also be part of routine check-ups or during pregnancy to assess overall health.

How Is the Test Performed?

A small amount of blood is drawn from a vein, usually in your arm, using a needle. The blood sample is then sent to a lab for testing. The test typically takes a few minutes, and you may feel a slight pinch or discomfort during the procedure.

What Are Common Results?

Results are usually reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While specific reference ranges can vary by lab, lower or higher than expected levels may signal potential health concerns.

What Do Results Mean?

Glucose levels that are too high (hyperglycemia) or too low (hypoglycemia) can cause symptoms like dizziness, fatigue, or confusion. Chronic high glucose levels are linked to diabetes and its complications, while low levels may indicate insulin issues or other medical conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Blood Sugar

Frequently asked questions

What causes abnormal glucose levels?
Abnormal glucose levels can result from conditions like diabetes, hormonal imbalances, infections, stress, or certain medications. Lifestyle factors, such as diet and physical activity, also play a significant role in blood sugar regulation.
How often should I get this test?
The frequency depends on your health status. If you have diabetes, your doctor may recommend testing every few months or more often. Otherwise, routine tests may be part of annual check-ups or as needed for specific symptoms or risk factors.
Can lifestyle changes affect my glucose test results?
Yes, diet, exercise, hydration, and stress levels can impact blood sugar. For example, eating a balanced meal or staying hydrated may help stabilize glucose levels. Always follow your doctor’s instructions for fasting or preparation before the test.
  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