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Glucose measured 15 hours postprandially in serum/plasma

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

This test checks your blood sugar level 15 hours after eating, helping assess how your body manages glucose over time.

Quick summary

["Understanding how your body processes sugar after meals is key to managing blood glucose levels."]

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

Key facts at a glance

LOINC
26779-9
Short code
Glucose 1.5h p Lac PO SerPl-mCnc
Synonyms
Glucose 1.5h p Lac PO SerPl-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 This Test Is Done

Doctors may order this test if you have diabetes, prediabetes, or symptoms like frequent hunger, fatigue, or unexplained weight changes. It helps evaluate long-term glucose control, especially in people with type 2 diabetes or insulin resistance.

How the Test Works

A blood sample is taken from a vein in your arm. The sample is processed to measure glucose concentration using a high-performance liquid chromatography (HPLC) method, which detects the sugar level accurately over time.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about any medications, especially those affecting blood sugar. Avoid eating or drinking anything except water for 8 hours before the test if instructed.

What the Results Mean

Results help identify patterns in your glucose levels, such as whether your body responds well to meals or if there’s a need for further management strategies. Abnormal results may indicate poor glucose control or underlying metabolic issues.

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

15-Hour Post-Meal Glucose (Serum/Plasma)

Frequently asked questions

What does a high or low result indicate?
High levels may suggest insulin resistance, diabetes, or poor metabolic health. Low levels could indicate hypoglycemia or other conditions affecting glucose metabolism. Always discuss results with your healthcare provider for personalized interpretation.
How often should I get this test?
Your doctor will determine the frequency based on your health status, treatment plan, and medical history. Regular monitoring helps track progress and adjust treatments as needed.
Can I eat or drink before this test?
Follow your doctor’s instructions precisely. Typically, you’ll need to fast for 8 hours before the test, but avoid eating or drinking anything except water unless otherwise directed.
  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