Overnight fasting plasma glucose concentration
This test measures the amount of glucose (sugar) in your blood after you’ve fasted for at least 8 hours. It helps assess your blood sugar levels and overall risk for diabetes or other metabolic conditions.
["A fasting blood sugar test checks how your body processes sugar, aiding diabetes screening and management."]
Key facts at a glance
- LOINC
- 46223-4
- Short code
- Glucose Overnight Dial fld-sCnc
- Synonyms
- Glucose Overnight Dial fld-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 This Test Matters
Your fasting blood sugar test is important because it provides a snapshot of your body’s ability to regulate blood glucose. High levels may indicate diabetes or insulin resistance, while consistently low levels could signal other health concerns.
What to Expect Before the Test
Before the test, you’ll need to fast (not eat or drink anything except water) for at least 8 hours. Your provider will give you specific instructions to follow. Bring any medications you’re currently taking, as some may affect your results.
How the Test Is Performed
A healthcare professional will draw a small amount of blood from a vein in your arm using a sterile needle. The blood sample is then sent to a lab for analysis. The test is quick and typically painless, though you may feel a slight pinch during the procedure.
What the Results Mean
Results are reported as a concentration of glucose in your plasma. While exact reference ranges vary by lab, a result above a certain threshold may signal abnormal blood sugar levels, prompting 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.
This test is a key part of diagnosing type 1 or type 2 diabetes, prediabetes, or other metabolic disorders. It helps monitor long-term blood sugar control in people with diabetes and assesses risk factors for cardiovascular disease or kidney problems.
Short name
Fasting Blood Sugar (Plasma)
Frequently asked questions
What does a fasting blood sugar test measure?
How long should I fast before this test?
Can I take my usual medications before the test?
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