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Glucose, measured as mass concentration in serum/plasma

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

This test checks the amount of glucose (sugar) in your blood, which helps assess how well your body is using energy and managing blood sugar levels.

Quick summary

["Glucose levels provide critical insight into diabetes, metabolism, and overall health."]

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

Key facts at a glance

LOINC
55517-7
Short code
GH 1h p Gc SerPl-mCnc
Synonyms
GH 1h p Gc 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 Is This Test Done?

Your healthcare provider may order this test to diagnose or monitor conditions like diabetes, high or low blood sugar, or to check for metabolic issues. It’s also used during pregnancy (e.g., gestational diabetes) or before surgeries to ensure stable blood sugar.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast (not eat or drink) for 8–12 hours before the test if it’s a fasting glucose check. Bring any medications you’re taking and let your lab staff know if you’re pregnant, have diabetes, or are on certain medications.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. The sample is sent to a lab where glucose levels are measured using a specialized test method. The process usually takes a few minutes.

What Are the Results?

Results are reported as a mass concentration (typically in milligrams per deciliter, mg/dL, or millimoles per liter, mmol/L). Your provider will interpret the results in the context of your health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High glucose levels may indicate diabetes, prediabetes, or other metabolic disorders. Low levels can signal insulin issues, stress, or certain medical conditions. Frequent monitoring helps manage long-term health risks like nerve damage, kidney problems, or heart disease.

Short name

Serum/Plasma Glucose

Frequently asked questions

How often should I get this test?
The frequency depends on your health status. For example, people with diabetes may test monthly or more often, while others may need it less frequently. Follow your provider’s recommendations.
What does a 'fasting' test mean?
A fasting test means you avoid eating or drinking (except water) for a set period (usually 8–12 hours) before the blood draw to get an accurate measure of your blood sugar when your body isn’t processing food.
Can I take my diabetes medication before the test?
Yes, but always check with your provider first. Some medications (like insulin) may need to be adjusted or skipped, depending on the test type and your specific condition.
  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