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Glucose (Serum/Plasma)

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

This test measures the amount of glucose, a type of sugar, in your blood. It helps assess how well your body is using energy and managing blood sugar levels.

Quick summary

["Glucose levels can indicate diabetes, hypoglycemia, or other metabolic conditions."]

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

Key facts at a glance

LOINC
53474-3
Short code
Glucose 4 AM specimen SerPl-sCnc
Synonyms
Glucose 4 AM specimen SerPl-sCnc
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 Is This Test Done?

Your doctor may order this test to check for diabetes or prediabetes, monitor blood sugar control in people with diabetes, evaluate symptoms like excessive thirst or fatigue, or assess conditions like liver disease or kidney problems that can affect glucose metabolism.

What to Expect Before the Test

For blood tests, you’ll typically have a small needle inserted into your arm to draw blood. If you’re fasting (not eating or drinking anything except water) for this test, follow your doctor’s instructions. Avoid smoking or caffeine before the test if advised.

What Happens During the Test

A healthcare professional will collect a small sample of blood from a vein in your arm. The sample is then sent to a lab for analysis. The process usually takes a few minutes.

What to Expect After the Test

You may feel slight bruising or soreness at the injection site, but this usually goes away quickly. Avoid heavy lifting or strenuous activity for a few hours afterward.

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

What does a normal glucose level mean?
There’s no single ‘normal’ range for everyone, as it can vary based on factors like age, health status, and whether you’re fasting. Your doctor will interpret results in the context of your medical history and other tests.
How often should I get this test?
Your doctor will determine the frequency based on your health needs. People with diabetes may need tests more often than others, possibly every few months or annually.
Can lifestyle changes affect my glucose test results?
Yes, diet, exercise, and stress can influence blood sugar levels. If you’re making changes, discuss them with your doctor 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