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Glucose in Serum (Plasma) by Enzymatic Method

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

This test measures the amount of glucose (sugar) in your blood serum or plasma, often used to monitor blood sugar levels.

Quick summary

["A simple blood test to check your blood sugar levels."]

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

Key facts at a glance

LOINC
47774-5
Short code
GH pre Arg SerPl-aCnc
Synonyms
GH pre Arg SerPl-aCnc
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?

Doctors may order this test to diagnose or monitor conditions like diabetes, high blood sugar, or to check for hypoglycemia (low blood sugar). It can also be used during pregnancy to screen for gestational diabetes or before surgeries to assess your overall health.

What to Expect Before the Test

You may be asked to fast (not eat or drink anything except water) for 8–12 hours before the test, depending on your doctor’s instructions. If you’re pregnant or have certain conditions, fasting rules may differ. Bring any medications you’re taking to your appointment.

What Happens During the Test?

A healthcare provider will draw a small amount of blood from a vein in your arm using a needle. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The blood is then sent to a lab for analysis.

What Do the Results Mean?

Results are typically reported in milligrams per deciliter (mg/dL). High levels may indicate diabetes or other metabolic issues, while very low levels could signal hypoglycemia or other health concerns. Your doctor will interpret results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum/Plasma Glucose

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, exercise, and weight, also play a role. If you notice frequent fluctuations, discuss them with your doctor.
How often should I get this test?
Your doctor will determine how often you need this test based on your health status, medical history, and symptoms. For example, people with diabetes may need tests every few months, while others may only need them once a year or less.
Can I eat or drink anything before the test?
Typically, you’ll need to fast for 8–12 hours before the test unless your doctor advises otherwise. Always follow your healthcare provider’s specific instructions to ensure accurate results.
  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