Glucose in Plasma (Fasting, 50-Gram Oral Glucose Tolerance Test)
This test measures your blood sugar level after drinking a sugary drink. It helps check how your body handles glucose, which is important for managing blood sugar control.
["Assesses how your body responds to glucose, useful for diabetes screening and management."]
Key facts at a glance
- LOINC
- 20441-2
- Short code
- Glucose p 50 g Glc SerPl-mCnc
- Synonyms
- Glucose p 50 g Glc 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
What Is This Test For?
A 50-gram oral glucose tolerance test involves drinking a sweet liquid containing 50 grams of glucose. Your blood sugar is then measured at specific times—typically before drinking and 1 hour after—to evaluate how your body processes glucose. This test is often used to screen for conditions like diabetes or gestational diabetes.
When Might You Need This Test?
You may need this test if you have symptoms of high blood sugar (e.g., frequent urination, excessive thirst) or if your doctor suspects prediabetes, diabetes, or gestational diabetes. It’s also sometimes used during pregnancy or if you have risk factors like obesity, a family history of diabetes, or high blood pressure.
How Is the Test Performed?
Before the test, you’ll fast for 8–12 hours. After drinking the glucose solution, your blood is drawn at set intervals (usually 1 hour post-drink) to check blood sugar levels. The test is quick but requires careful preparation to ensure accurate results.
What Are the Results Used For?
Results help determine if your body has trouble processing glucose, which can indicate diabetes or prediabetes. High levels may signal impaired glucose tolerance, while consistently low levels (if fasting) could warrant further evaluation.
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.
Clinical Significance: This test is critical for diagnosing glucose intolerance, a precursor to type 2 diabetes. Abnormal results may prompt additional testing, lifestyle changes, or medication to manage blood sugar levels effectively.
Short name
50g Oral Glucose Tolerance Test Glucose
Frequently asked questions
Why did my doctor order this test?
What should I do before the test?
Will the test hurt?
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