Glucose (Plasma or Serum) – Quantitative Measurement
This test measures the amount of glucose (sugar) in your blood, typically drawn from a vein or capillary site. Glucose levels help assess how well your body is using energy and managing blood sugar.
["Glucose levels provide critical insight into diabetes management and metabolic health."]
Key facts at a glance
- LOINC
- 21308-2
- Short code
- Glucose 105M p chal SerPl-mCnc
- Synonyms
- Glucose 105M p chal 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
Why Is This Test Done?
Your healthcare provider may order this test to diagnose or monitor conditions like diabetes, check for high or low blood sugar, evaluate metabolic disorders, or assess how your body responds to medications or treatments. It can also be used during pregnancy to screen for gestational diabetes or to monitor glucose control in people with known diabetes.
What to Expect Before the Test
For a blood draw, you may fast (not eat or drink) for 8–12 hours before the test, depending on your doctor’s instructions. If fasting is not required, you can eat and drink normally. Avoid smoking or caffeine before the test. Tell your provider about any medications you’re taking, as some may affect results.
What Happens During the Test?
A healthcare professional will clean the skin at your chosen site (usually an arm) and insert a small needle to draw blood. You may feel a slight pinch, but it usually takes only a few seconds. The blood sample is then sent to a lab for analysis.
What Happens After the Test?
After the blood is drawn, the site will be covered with a bandage or gauze. You can resume normal activities immediately unless your provider gives specific instructions. If you had a fasting test, you can eat and drink once the test is complete, unless directed otherwise.
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.
High glucose levels may indicate diabetes, prediabetes, or other metabolic issues, while persistently low levels could signal hypoglycemia or other endocrine problems. Regular monitoring helps prevent complications like nerve damage, kidney disease, or cardiovascular risks. Your results will guide your doctor’s decisions about treatment, lifestyle changes, or further testing.
Short name
None
Frequently asked questions
How long does it take to get my results?
Can I eat or drink before this test?
What if my glucose level is outside the expected 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