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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. Glucose is the primary energy source for your body’s cells.

Quick summary

["Glucose levels help assess how your body uses energy and can indicate health risks like diabetes."]

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

Key facts at a glance

LOINC
16903-7
Short code
Glucose Vitf-mCnc
Synonyms
Glucose Vitf-mCnc
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 healthcare provider may order this test to check for conditions like diabetes, high or low blood sugar, or to monitor treatment effectiveness. It’s also used during pregnancy to screen for gestational diabetes or to evaluate metabolic health.

What to Expect Before the Test

For blood tests, you may need to fast (not eat or drink except water) for 8–12 hours before the draw, depending on your doctor’s instructions. If fasting isn’t required, you can eat normally. For urine tests, you’ll collect a sample in a clean container.

What Happens During the Test?

Blood tests are typically done by a phlebotomist who will insert a small needle into a vein in your arm. You may feel a brief pinch, but it usually doesn’t cause significant discomfort. Urine tests involve urinating into a container provided by the lab.

What to Expect After the Test

After a blood draw, you may feel slight bruising or soreness at the site, but this usually fades quickly. For urine tests, there’s no recovery time. Results are usually available within a few days, depending on lab processes.

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 long does it take to get results?
Results are typically ready within 1–3 business days, but this can vary by lab. Your doctor will contact you once they’re available, especially if further action is needed.
Can I eat or drink before this test?
Fasting instructions depend on the test. Blood glucose tests often require fasting for 8–12 hours, while some tests may allow water. Always follow your doctor’s specific instructions to ensure accurate results.
What does a ‘fasting’ glucose test mean?
A fasting glucose test measures your blood sugar after not eating for a set period. It helps assess how your body processes glucose and can detect diabetes or other metabolic issues that may not show up with normal eating.
  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