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Glucose in Serum (or Plasma) by Enzymatic Method

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

This test measures the amount of glucose (sugar) in your blood, typically drawn from a vein or collected in a serum or plasma sample. It helps assess how well your body is using sugar for energy and managing blood sugar levels.

Quick summary

["This test helps monitor blood sugar control, especially important for diabetes management."]

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

Key facts at a glance

LOINC
74790-7
Short code
Glucose HBT Pnl ExG
Synonyms
Glucose HBT Pnl ExG
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
70
Ref high
100
Critical range
50 N/A – 400 N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
CPT
82947
SNOMED
260395008
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 Is Done

Doctors order glucose tests to check for conditions like diabetes, hypoglycemia (low blood sugar), or to evaluate how your body processes sugar. It may also be used during pregnancy, before surgeries, or to monitor chronic illnesses affecting metabolism.

What to Expect Before the Test

You may be asked to fast (not eat) for 8–12 hours before the test, depending on the procedure. For fasting tests, drink only water. If you’re not fasting, you may eat a standard meal. Avoid smoking or caffeine before testing, as they can affect results.

The Testing Process

A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause pain. The blood is then sent to a lab for analysis using an enzymatic method to measure glucose concentration.

What the Results Mean

Results are typically reported as a numerical value (mg/dL or mmol/L), but exact ranges vary by lab and clinical context. High or low values may indicate underlying health issues that need further evaluation by your doctor.

Reference range

Fasting: 70-100 mg/dLN/A

Specimen: serum

Fasting for 8-12 hours required. Water is permitted. Avoid chewing gum and smoking before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Glucose Level

Frequently asked questions

How often should I get this test?
Frequency depends on your health status. People with diabetes may need tests every few months, while others may only need occasional checks. Follow your doctor’s recommendations.
What can affect my test results?
Fasting, exercise, stress, medications (like insulin or diabetes drugs), recent meals, or even the time of day can influence glucose levels. Avoiding these factors helps ensure accurate results.
Do I need to prepare differently if I’m pregnant?
Yes, pregnant women may need fasting glucose tests during the first trimester or for gestational diabetes screening. Your doctor will guide specific preparation, such as timing or diet restrictions.
  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