Fasting Insulin Test
Fasting Insulin Test is a laboratory test you can order directly. A fasting insulin test measures the amount of insulin in your blood after you have not eaten for several hours. Insulin is a hormone that moves sugar from your blood into your cells. Clinicians order this test to look at how well your body responds to insulin and to help assess metabolic health.
- Sample type
- blood
- Category
- Metabolic & Glucose
- Turnaround
- 1-3 business days
- Price
- $29
- Referral
- Not required
A fasting insulin test measures the amount of insulin in your blood after you have not eaten for several hours. Insulin is a hormone that moves sugar from your blood into your cells. Clinicians order this test to look at how well your body responds to insulin and to help assess metabolic health.
What it measures
- Insulin level — The amount of insulin in your blood at the time of the draw.
- Fasting glucose (often paired) — Blood sugar measured at the same time, which helps put the insulin result in context.
- Estimated insulin resistance — Some labs calculate a ratio from insulin and glucose; this is an estimate, not a diagnosis.
Who it is for
A clinician may order a fasting insulin test if you have risk factors for insulin resistance, such as elevated blood sugar, excess weight around the waist, or polycystic ovary syndrome (PCOS). It may also be used to monitor a known metabolic condition.
Preparation
You will usually need to fast (no food or drink except water) for about 8 to 12 hours before the blood draw. Follow the specific instructions from your clinician or lab, since timing can vary.
Results and what they mean
Results are reported as a number with a reference range that varies by lab. A single value is not a diagnosis; your clinician interprets it alongside your glucose, symptoms, and history. This is general information only and not medical advice.
How to order this test
- Choose the test and place a confidential order online.
- Select a certified collection site and pick a time that suits you.
- Have your specimen collected — most draws take only a few minutes.
- Review results in a secure portal, typically within 1–3 days.
Preparation, hours, and pricing vary by site; confirm details directly with the lab before your visit.
Availability by state
Direct-access online ordering for the fasting insulin test is available in most states. It is currently unavailable in 6 states:
Everywhere else you can order confidentially and collect your sample at a certified site. Browse by state →
Frequently asked questions
Do I need to fast for this test?
Yes, most labs ask for an 8- to 12-hour fast. Water is usually fine. Confirm the exact fasting time with your clinician or lab.
Can I take my medications before the test?
Ask your clinician. Some medicines can affect insulin levels, and they can tell you whether to take them as usual or adjust the timing.
What does a high insulin level mean?
It may suggest your body is making extra insulin to keep blood sugar in range. Only your clinician can explain what your result means for you.
How long until I get results?
Results are typically available in 1 to 3 business days, though this can vary by lab.