Glucose (Serum or Plasma) Concentration
This test measures the amount of glucose (sugar) present in your blood, typically drawn from a vein or collected in a tube. Glucose is a key energy source for your body’s cells.
["Your blood sugar levels help determine how your body uses energy and manages metabolism."]
Key facts at a glance
- LOINC
- 54251-4
- Short code
- Glucose 20M p Gc SerPl-sCnc
- Synonyms
- Glucose 20M p Gc 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 This Test Is Done
Doctors order glucose tests to check for conditions like diabetes, monitor blood sugar levels in people with diabetes, evaluate symptoms of low blood sugar (hypoglycemia), or assess metabolic health. It may also be used during pregnancy or before certain surgeries.
What to Expect Before the Test
No special preparation is needed for most glucose tests. If fasting is required (e.g., for a fasting glucose test), avoid eating or drinking anything except water for 8–12 hours before the test. Tell your healthcare provider about any medications you’re taking, as some may affect results.
During the Test Process
A healthcare professional will insert a small needle into a vein in your arm to draw blood. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood sample is then sent to a lab for analysis.
What the Results Mean
Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While reference ranges vary by lab, abnormal results may signal high or low blood sugar, which can indicate diabetes, prediabetes, or other metabolic disorders. Your doctor 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.
Glucose levels are critical for diagnosing diabetes (e.g., fasting glucose ≥126 mg/dL or random glucose ≥200 mg/dL with symptoms) or monitoring long-term control. Repeatedly high or low levels can damage organs over time, so consistent monitoring is important for people with diabetes or prediabetes. Abnormal results may also prompt further testing, such as an HbA1c or oral glucose tolerance test.
Short name
Glucose Level
Frequently asked questions
How often should I get this test?
What can affect my glucose test results?
What if my glucose level is outside the normal range?
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