Oral Glucose Tolerance Test (OGTT) with 75-gram glucose load
This test measures how your body processes glucose (sugar) after drinking a sugary liquid. It helps check for diabetes or how well your pancreas produces insulin.
["Assesses blood sugar control after consuming a controlled sugar dose to detect diabetes or prediabetes risk."]
Key facts at a glance
- LOINC
- 14996-3
- Short code
- Glucose pre 75 g Glc PO SerPl-sCnc
- Synonyms
- Glucose pre 75 g Glc PO 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
What to Expect Before the Test
You’ll start by fasting overnight (usually 8–12 hours). The next morning, you’ll drink a sweet liquid containing 75 grams of glucose. Blood samples will be taken at intervals—typically before drinking and 30 minutes, 1 hour, 2 hours, and sometimes 3 hours afterward.
How the Test Works
Your blood sugar levels are measured using a simple blood draw. The test checks how your body responds to the glucose, helping doctors identify if your pancreas works normally or if insulin resistance is present.
Why It’s Done
Doctors may recommend this test if you have symptoms like excessive thirst, fatigue, or unexplained weight changes. It’s also used for pregnant women (to screen for gestational diabetes) or those with a family history of diabetes.
What to Prepare
Follow fasting instructions strictly—no food or drinks (except water) for the specified time. Wear comfortable clothing for blood draws, and bring any medications you’re currently taking (ask your doctor if you should pause insulin or other diabetes meds).
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.
Abnormal results may indicate diabetes (high blood sugar) or impaired glucose tolerance. Low blood sugar (hypoglycemia) after the test could signal overproduction of insulin or other metabolic issues. Your doctor will interpret results in context with your symptoms and medical history.
Short name
OGTT 75g
Frequently asked questions
How long does the test take?
Will I feel any pain or discomfort?
Can I eat or drink anything after the 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