Glucose concentration in serum (pre-challenge)
This test measures the amount of glucose (sugar) in your blood serum before you consume a specific food or drink, often used to assess how your body responds to glucose.
["This test helps evaluate blood sugar levels before a glucose tolerance test."]
Key facts at a glance
- LOINC
- 40148-9
- Short code
- Glucose pre chal SerPl-sCnc
- Synonyms
- Glucose pre chal 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 check how well your body processes glucose. It’s often part of a glucose tolerance test, where you’ll drink a sugary solution afterward to see how your blood sugar changes over time.
What to Expect Before the Test
You’ll likely fast for 8–12 hours before the test. Bring any medications you’re currently taking and let your provider know if you have any allergies or conditions that might affect results. Avoid smoking or chewing gum right before the blood draw.
How the Test Works
A small needle will be inserted into your arm to draw a blood sample from your vein. The blood is sent to a lab where it’s analyzed for glucose levels using an automated method, such as enzymatic testing.
What the Results Mean
Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While exact reference ranges vary by lab, higher or lower-than-expected levels may signal potential issues that need 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.
Abnormally high or low glucose levels in this pre-challenge test can indicate impaired glucose metabolism. For example, persistently high levels may suggest diabetes, while low levels could signal hypoglycemia or other metabolic disorders. Your provider will use these results alongside other tests and symptoms to guide diagnosis and treatment.
Short name
Glucose (Serum, Pre-Challenge)
Frequently asked questions
What does a ‘pre-challenge’ test mean?
Can I eat or drink anything before this test?
Will I feel any pain or discomfort during the blood draw?
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