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Glucose in Serum or Plasma (Mass Concentration)

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

This test measures the amount of glucose, a type of sugar, in your blood. It helps assess your blood sugar levels and overall metabolic health.

Quick summary

["A simple blood test to check how your body uses sugar for energy."]

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

Key facts at a glance

LOINC
56562-2
Short code
GH 6.5h p chal SerPl-mCnc
Synonyms
GH 6.5h p chal SerPl-mCnc
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 This Test Matters

Glucose levels are crucial for managing energy, brain function, and preventing complications like diabetes. Abnormal results may signal conditions such as high or low blood sugar, diabetes, or other metabolic disorders.

What to Expect Before the Test

You may be asked to fast (not eat or drink except water) for 8–12 hours before the test, depending on your doctor’s instructions. Bring any medications you’re currently taking to your appointment.

How the Test Works

A small blood sample is taken from your arm or finger. The sample is sent to a lab where glucose levels are measured using an automated method, such as enzymatic analysis.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). Low or high values may prompt further testing or lifestyle adjustments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Serum/Plasma Glucose

Frequently asked questions

Glucose testing is foundational in diagnosing diabetes, monitoring prediabetes, and evaluating conditions like hypoglycemia (low blood sugar) or hyperglycemia (high blood sugar). Repeated testing may be needed to track trends over time.
This test is often performed as part of a routine checkup, during pregnancy, or if you have symptoms like excessive thirst, fatigue, or frequent urination.
What if I have questions about my results? Your doctor will explain what they mean in the context of your health and may recommend follow-up tests if needed.
How often should I get this test? Your doctor will determine the best schedule based on your health status, such as every 3–6 months for stable diabetes management.
Can I eat or drink anything before the test? Follow your doctor’s instructions carefully—some tests require fasting, while others allow water.
Will the test hurt? A small needle is used to draw blood, which may cause a brief sting. Most people find it quick and manageable.
  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