Glucose (Fasting, Serum)
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 metabolic health.
["A fasting blood glucose test checks if your blood sugar is within a healthy range after not eating."]
Key facts at a glance
- LOINC
- 26551-2
- Short code
- Glucose 5h p Glc Ur Ql Strip
- Synonyms
- Glucose 5h p Glc Ur Ql Strip
- 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
- Method
- test-strip
- 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 Matters
Your doctor may order this test to diagnose or monitor conditions like diabetes, prediabetes, or to check for high blood sugar levels. It’s also used during pregnancy (gestational diabetes screening) or if you have symptoms like excessive thirst, frequent urination, or unexplained weight changes.
When You Might Need It
You’ll typically need to fast (not eat or drink anything except water) for 8–12 hours before this test. Your doctor will provide specific instructions. Common triggers include routine check-ups, diabetes screening, or before certain medications or procedures.
What to Expect During the Test
A healthcare provider will draw blood from a vein in your arm. You may feel a small pinch, but it usually doesn’t cause significant discomfort. The blood sample is sent to a lab for analysis.
What the Results Mean
Results are compared to general reference ranges (not provided here), but your doctor will interpret them in the context of your health history and symptoms. High or low results may signal underlying 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.
Clinical Significance
Short name
Fasting Blood Glucose
Frequently asked questions
What questions do patients often ask about this test?
Can I take my usual medications before the test? Some medications (like insulin or diabetes meds) may need adjustment. Always follow your doctor’s instructions to avoid interfering with results.
How often should I get this test? Frequency depends on your health status. People with diabetes may test more often, while others may need it less frequently (e.g., every 1–3 years). Follow your healthcare provider’s recommendations.
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