Glucose in Serum (Fasting or Random)
This test measures the amount of glucose (sugar) present in your blood serum. It helps assess your blood sugar levels, which is important for managing conditions like diabetes.
["This test checks your blood sugar to help prevent complications from high or low sugar levels."]
Key facts at a glance
- LOINC
- 33178-5
- Short code
- OFD from GA.ASUM00
- Synonyms
- OFD from GA.ASUM00
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- us-estimated-from-asum
- 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
Your healthcare provider may order this test to diagnose or monitor diabetes, check for signs of low blood sugar (hypoglycemia), evaluate how your body processes glucose, or assess for conditions like liver disease or stress responses.
What to Expect Before the Test
For fasting glucose tests, you’ll typically fast (not eat or drink except water) for 8–12 hours before the test. For random glucose tests, you can eat normally. Bring any medications you’re taking and let your lab know if you’re pregnant, have diabetes, or are on certain medications.
During the Test
A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the procedure usually takes just a few minutes. You can resume normal activities immediately afterward.
What the Results Mean
Results are interpreted by your healthcare provider based on your medical history and symptoms. Abnormally high or low glucose levels may signal diabetes, metabolic disorders, or other health concerns that require further evaluation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Glucose levels are critical for diagnosing diabetes (fasting glucose ≥126 mg/dL or random ≥200 mg/dL with symptoms) and monitoring long-term blood sugar control. Chronic high glucose can damage blood vessels and nerves, while chronic low glucose can cause weakness, dizziness, or confusion. This test is also used to screen for prediabetes or to assess glucose metabolism disorders.
Short name
Serum Glucose
Frequently asked questions
How often should I get this test?
What can affect my glucose test results?
What if my glucose 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