Quick Facts
- Sample: Blood
- Fasting: Fasting for at least 12 hours is required. Stop biotin consumption at least 72 hours before collection. Follow a high-carbohydrate diet for 3 days before testing.
- Turnaround: 4-5 business days. May take longer based on weather, holiday, or lab delays.
Note: This test is commonly ordered with the 3-Hour Glucose Tolerance Test (GTT), 4 Specimen so insulin and glucose results can be compared across the same time points.
What This Test Measures
This test measures the amount of insulin in your blood as it responds to glucose, using three separate blood specimens. Rather than a single fasting insulin value, this test captures insulin response across three specimens, giving a broader picture of how your body releases insulin than one draw alone.
This test evaluates insulin response, not blood glucose itself, and results are reported for each of the three specimens individually. It is a distinct test from a glucose tolerance test, though the two are commonly ordered together so insulin and glucose results can be compared across the same time points.
Benefits
- Helps screen for hypoglycemia based on insulin response to glucose.
- Helps screen for suspected insulin resistance.
- Captures insulin levels across three separate blood specimens.
- Can support evaluation of low blood sugar symptoms.
- Pairs with glucose tolerance testing for side-by-side comparison.
Who Is This Test For?
- People experiencing symptoms such as rapid heartbeat, sweating, or dizziness.
- People experiencing signs commonly associated with insulin resistance.
- Individuals with a fasting glucose level above 100 mg/dL.
- Those whose provider wants insulin response tracked across multiple specimens.
- Individuals also being evaluated with a glucose tolerance test.
How It Works
- Order Your Test Online
- Visit a Local Lab
- Get Results Online
FAQ
1. Do I need to fast or prepare for this test?
Yes. Fasting for at least 12 hours is required before your blood draw. You should also stop consuming biotin at least 72 hours prior to collection, and follow a high-carbohydrate diet for the 3 days leading up to testing.
2. How quickly will I get results?
Results are typically available in 4-5 days, though this timeframe may take longer due to weather, holidays, or other lab delays.
3. What can my results tell me?
Each of the three specimens reports an insulin level reflecting how your body responded to glucose at that point in testing. Together, these values may help your provider evaluate patterns consistent with hypoglycemia or insulin resistance. A single specimen result does not tell the full story on its own, since the test is designed to look at insulin response across all three draws.
4. What factors can affect my results?
Not following the required 12-hour fast can affect the accuracy of your insulin levels. Biotin supplements taken within 72 hours of collection may also interfere with results, which is why this window matters. The high-carbohydrate diet in the days before testing is part of the required preparation and helps standardize how your body responds to glucose during the test.
5. How do I interpret the results?
Interpreting your insulin response results depends on your fasting status, adherence to the pre-test diet, your symptoms, and any related testing you've had, such as a glucose tolerance test. A single high or low value from one specimen isn't a standalone answer. Discuss your full set of results with a qualified healthcare provider who can weigh them alongside your medical history.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
6. What should I do if my results are abnormal?
Reviewing abnormal results with a qualified healthcare provider is the appropriate next step. Your provider can help determine whether additional evaluation or testing makes sense based on your full clinical picture. This test does not diagnose hypoglycemia, insulin resistance, or diabetes on its own, and an abnormal result does not automatically mean treatment is needed.
Pre-test preparation
Fasting for at least 12 hours is required. Stop biotin consumption at least 72 hours prior to the collection. Follow a high-carbohydrate diet for 3 days prior to testing.
