Glucose in Serum/Plasma (24-Hour Average)
This test measures the average level of glucose (sugar) in your blood over a 24-hour period, using a sample of your serum or plasma. It helps assess how well your body manages blood sugar over time.
["Understanding your long-term blood sugar control is key to managing diabetes or prediabetes."]
Key facts at a glance
- LOINC
- 49688-5
- Short code
- GTT p 75 g Glc PO SerPl-Imp
- Synonyms
- GTT p 75 g Glc PO SerPl-Imp
- Category
- glucose
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- true
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 for You
Unlike a single blood sugar check, this test gives a clearer picture of how consistently your blood sugar stays within healthy ranges. It’s particularly useful for people with diabetes to track trends and adjust treatment plans.
How the Test Works
Your healthcare provider will collect a blood sample from you. The glucose levels from multiple samples over 24 hours are analyzed to calculate an average. This method helps reduce the impact of short-term fluctuations (like meals or stress) on your results.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic study. Wear comfortable clothing and bring any medications you’re currently taking.
Common Causes for Testing
This test is often ordered for people with diabetes to monitor glucose control, those at risk of diabetes, or individuals with symptoms like frequent urination, extreme thirst, or unexplained weight changes.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated results may indicate poor glucose management, which can increase the risk of long-term complications like nerve damage, kidney disease, or heart problems. Lower-than-normal results might suggest hypoglycemia (low blood sugar) or other metabolic issues that need attention.
Short name
Average Blood Sugar (24h)
Frequently asked questions
What Does My Result Mean?
Will I Need to Take Any Medications or Changes to My Diet?
Can I Still Eat Normally Before This 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