Glucose measured 4 hours post-meal via high-performance liquid chromatography (HPLC) in plasma
This test checks your blood sugar level four hours after eating to assess how your body handles glucose over time.
["Helps evaluate glucose metabolism and diabetes management effectiveness."]
Key facts at a glance
- LOINC
- 42629-6
- Short code
- Glucose 4h p Lac PO Ur-mCnc
- Synonyms
- Glucose 4h p Lac PO Ur-mCnc
- Category
- glucose
- Sample
- urine
- Container
- Sterile urine container
- 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
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your healthcare provider may order this test if you have diabetes or are at risk for it, or if you’re experiencing symptoms like frequent urination, excessive thirst, or unexplained weight changes. It can also help monitor how well your current treatment plan is working.
How the Test Works
A blood sample is taken from a vein, usually in your arm. The sample is processed to measure glucose levels using HPLC, a precise method that separates and identifies glucose molecules. Results are reported as a mass concentration of glucose in plasma.
What to Expect Before the Test
You’ll typically fast for 8–12 hours before the test, but this 4-hour post-meal test does not require fasting. If you’re taking diabetes medications, ask your provider whether to pause them before the test. Bring any recent lab results or medication lists to your appointment.
What the Results Mean
While specific ranges vary by lab, abnormal results may indicate poor glucose control. High levels could signal diabetes or insulin resistance, while low levels may suggest hypoglycemia or other metabolic issues. Your provider will interpret results in the context of your overall health.
Reference range
Fasting: 70-100 mg/dLN/A
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.
This test is critical for diagnosing and managing diabetes, particularly type 2, by assessing how your body processes glucose after eating. It helps identify whether your current treatment—such as diet, medication, or insulin—is effective. Persistently high or low results may prompt further evaluation for underlying conditions.
Short name
4-Hour Postprandial Glucose (Plasma, HPLC)
Frequently asked questions
What does a ‘4-hour post-meal’ test measure?
Can I eat or drink anything before this test?
How long will I need to wait for my results?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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