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Serum Glucose (Fasting) with High-Performance Liquid Chromatography (HPLC) Method

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

This test measures your blood sugar level after you’ve fasted for a set period, often used to assess how your body processes glucose.

Quick summary

["Fasting glucose helps check for diabetes or other blood sugar issues."]

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

Key facts at a glance

LOINC
30265-3
Short code
Glucose 1.3h p Glc SerPl-sCnc
Synonyms
Glucose 1.3h p Glc 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 healthcare provider may order this test to diagnose or monitor conditions like diabetes, prediabetes, or to evaluate symptoms such as excessive thirst, frequent urination, or unexplained weight changes. It’s also used in screening for metabolic disorders or before certain treatments.

What to Expect Before the Test

You’ll need to fast for 8–12 hours before the test, meaning no food or drink (except water) except for medications if approved. Avoid smoking and strenuous activity for a few hours beforehand. Bring any medications you’re taking to discuss with your provider.

How the Test Is Performed

A healthcare professional 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 significant discomfort. The blood sample is then sent to a lab for analysis using HPLC, a precise method to measure glucose concentration.

What the Results Mean

Results are typically reported as a mass concentration of glucose in your serum. While exact reference ranges vary by lab, higher or lower-than-expected levels may signal potential health concerns 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.

Clinical Significance

Short name

Fasting Serum Glucose (HPLC)

Frequently asked questions

What does a high fasting glucose level indicate?
A high fasting glucose level may indicate diabetes or prediabetes, where your body struggles to regulate blood sugar properly. Repeatedly high levels can damage blood vessels and organs over time, increasing risks for heart disease, nerve damage, or kidney problems. Your doctor may recommend lifestyle changes, medications, or further testing.
What does a low fasting glucose level indicate?
Low fasting glucose levels (hypoglycemia) can cause symptoms like shakiness, dizziness, or confusion. While less common in fasting tests, they may signal conditions like adrenal insufficiency or certain medications affecting blood sugar. Your doctor may adjust treatments or investigate underlying causes.
How often should I get this test?
Your doctor will determine the frequency based on your health status, medical history, and symptoms. Typically, people with diabetes check fasting glucose every few months, while others may need it less often or only during specific screenings (e.g., pregnancy, obesity, or family history of diabetes). Always follow your provider’s guidance.
  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