The short answer
Fasting insulin is the amount of insulin in your blood after a night without food. When your body stops responding well to insulin, your pancreas makes more to keep blood sugar normal, so a high level can be an early sign of insulin resistance.1 Labcorp’s range is 2.6 to 24.9 µIU/mL.5
- A good result
- With a normal blood sugar, about 2 to 6 µIU/mL. That’s far narrower than Labcorp’s range of 2.6 to 24.9,5 and no guideline sets a target, but many prevention-focused clinicians aim for it. It suggests your body responds well to insulin, and lower levels have gone with less diabetes, high blood pressure and heart disease in studies.6,10 Lower isn’t always better: a low insulin with a high glucose can mean your pancreas isn’t making enough.1
- If yours is high
- It often goes with insulin resistance. Losing extra weight and being more active improve it.1 Check your fasting glucose and HbA1c, which decide whether you have prediabetes.1
- Should you test?
- It’s an optional extra next to fasting glucose and HbA1c, the tests that diagnose prediabetes.1 It can hint at insulin resistance while your glucose is still normal, especially paired with glucose as HOMA-IR. It’s an estimate, not a diagnosis. There’s no agreed cutoff, and results differ between labs.1,4
Check your result
Type the number from your report. It stays on this page.
- Below range Under 2.6
- In range 2.6 to 24.9
- High 25.0 or more
Enter your result to see what it means and what to do next.
Got a result from another lab? Ask Picardo about it. The app explains your results, and a physician can follow up.
Labcorp’s range, not a guideline cutoff. No guideline sets one, and other labs’ insulin tests give different numbers, so these lines only fit a Labcorp result.4,5 The bar isn’t to scale.
Below the lab’s range
With a normal fasting glucose, a low insulin usually isn’t a concern. Your body needs little insulin to keep your blood sugar steady overnight. If your glucose is high too, low insulin can mean your pancreas isn’t making enough, as in type 1 diabetes.1
Not a worry if your glucose is normal. If it’s high, see a clinician in the next week or two.
- 1 Look at your fasting glucose from the same draw. If it’s 100 or more, show both results to a clinician.1
Within the lab’s range
Labcorp won’t flag this. But the range is wide, and a result near the top can still go with insulin resistance. In a US study of 5,314 adults without diabetes, the average was about 6, and people at 8.1 or more were more likely to develop diabetes than those at 3.4 or less.6 That study used a different insulin test, so its numbers are a guide, not cutoffs for your result.4 With a normal glucose, many prevention-focused clinicians aim for about 2 to 6.
Not a worry on its own.
- 1 Work out your HOMA-IR from this result and your fasting glucose, since your glucose changes what your insulin means.
- 2 If your result is in the upper part of the range, check your fasting glucose and HbA1c.1
- 3 If your glucose from the same draw was below the lab’s range, or you had shakiness or sweating that eased when you ate, show both results to a clinician soon.
Above the lab’s range
Your pancreas is making more insulin than most people’s after a fast. That often goes with insulin resistance, though one insulin result can’t diagnose it. Extra weight, especially around the waist or in the liver, is a common cause, and some medicines, including steroids, can cause it too.1 Check that you fasted, since a recent meal raises insulin.5
Worth acting on over the next few months. It isn’t urgent.
- 1 Check your fasting glucose and HbA1c to see whether your blood sugar has started to rise.1
- 2 Losing extra weight and being more active are the best ways to improve insulin resistance; see how to lower fasting insulin below.1
- 3 If you’re rechecking, use the same lab and fast for the same length of time.4,7
- 4 If your glucose from the same draw was below the lab’s range, or you had shakiness or sweating that eased when you ate, show both results to a clinician soon.
What is a normal fasting insulin level?
There’s no agreed healthy level for fasting insulin, and Labcorp’s range is wide.3,5 Results from other labs aren’t interchangeable, so these bands only fit a Labcorp result:4
Below the lab’s range
With a normal fasting glucose, a low insulin usually isn’t a concern. Your body needs little insulin to keep your blood sugar steady overnight. If your glucose is high too, low insulin can mean your pancreas isn’t making enough, as in type 1 diabetes.1
Not a worry if your glucose is normal. If it’s high, see a clinician in the next week or two.
- 1 Look at your fasting glucose from the same draw. If it’s 100 or more, show both results to a clinician.1
Within the lab’s range
Labcorp won’t flag this. But the range is wide, and a result near the top can still go with insulin resistance. In a US study of 5,314 adults without diabetes, the average was about 6, and people at 8.1 or more were more likely to develop diabetes than those at 3.4 or less.6 That study used a different insulin test, so its numbers are a guide, not cutoffs for your result.4 With a normal glucose, many prevention-focused clinicians aim for about 2 to 6.
Not a worry on its own.
- 1 Work out your HOMA-IR from this result and your fasting glucose, since your glucose changes what your insulin means.
- 2 If your result is in the upper part of the range, check your fasting glucose and HbA1c.1
- 3 If your glucose from the same draw was below the lab’s range, or you had shakiness or sweating that eased when you ate, show both results to a clinician soon.
Above the lab’s range
Your pancreas is making more insulin than most people’s after a fast. That often goes with insulin resistance, though one insulin result can’t diagnose it. Extra weight, especially around the waist or in the liver, is a common cause, and some medicines, including steroids, can cause it too.1 Check that you fasted, since a recent meal raises insulin.5
Worth acting on over the next few months. It isn’t urgent.
- 1 Check your fasting glucose and HbA1c to see whether your blood sugar has started to rise.1
- 2 Losing extra weight and being more active are the best ways to improve insulin resistance; see how to lower fasting insulin below.1
- 3 If you’re rechecking, use the same lab and fast for the same length of time.4,7
- 4 If your glucose from the same draw was below the lab’s range, or you had shakiness or sweating that eased when you ate, show both results to a clinician soon.
What is fasting insulin?
Think of insulin as a key that lets sugar into your cells. With insulin resistance, the locks get stiff, so your pancreas makes more keys to get the same job done. Fasting insulin counts the keys.
Insulin is the hormone your pancreas makes to move sugar out of your blood and into your cells. Extra weight, especially around the waist and in the liver, makes your body respond to insulin less well.1 Your pancreas makes up for it by making more. Type 2 diabetes develops when it can no longer make enough to keep blood sugar normal.1
Why don’t guidelines use fasting insulin?
No major guideline sets a cutoff for fasting insulin or uses it to diagnose anything. The American Diabetes Association diagnoses prediabetes and diabetes with glucose and HbA1c alone.1 The 2023 international PCOS guideline says insulin tests are of limited clinical value and shouldn’t be used in routine PCOS care.2 The Endocrine Society recommends against measuring insulin in children and teens with obesity, saying it has no diagnostic value.3
The main problems:
- Labs disagree. In a 2025 comparison of 12 insulin tests, only one fully matched the reference method, though all claimed to follow the same standard.4
- One result is noisy. In older adults retested about six weeks apart, fasting insulin varied by about 29% within the same person.7
- It’s a rough guide. In adult studies, fasting insulin explained only 5% to 50% of the differences in insulin sensitivity between people.3
What does high fasting insulin mean?
It goes with a higher risk of type 2 diabetes. In a US study of 5,314 adults without diabetes followed for about 8 years, people with a fasting insulin of 8.1 µIU/mL or more were about 3.8 times as likely to develop diabetes as people at 3.4 or less. That allowed for weight, age and family history.6
Once their fasting glucose was taken into account too, the gap shrank to about 1.6 times.6 So insulin adds something, but less than it seems once you know your glucose. That’s why it’s most useful combined with glucose, as HOMA-IR.
What raises fasting insulin:
- Extra weight, especially around the waist or in the liver1
- Too little physical activity1
- Polycystic ovary syndrome (PCOS)2
- Medicines that can cause insulin resistance or raise blood sugar, such as steroids, statins, thiazide diuretics, some HIV medicines and some antipsychotics1
- Eating before the test5
How to lower fasting insulin
- Losing extra weight
Extra weight causes some insulin resistance on its own, and losing it improves how well your body responds to insulin.1
- How much it helps
- A lot
- How sure we are
- Very sure
- Regular physical activity
Improves insulin resistance, and too little activity raises the risk of type 2 diabetes.1
- How much it helps
- Some
- How sure we are
- Very sure
- GLP-1 and related weight-loss drugs
In people with obesity or overweight without diabetes, tirzepatide lowered fasting insulin by 47% over 72 weeks, against 10% on placebo.8 They’re prescribed for weight, not for insulin itself.
- How much it helps
- A lot
- How sure we are
- Very sure
Because a single result can vary by about 29%, look for a trend over two or three tests rather than reading much into one change.7
Who should get a fasting insulin test?
Guidelines screen for prediabetes and diabetes with glucose and HbA1c.1 Insulin is an optional extra on top of those, never a replacement: a rough estimate of insulin resistance from a test that isn’t standardized between labs.4 It adds the most if:
- Your fasting glucose and HbA1c are normal, but you have signs or conditions linked to insulin resistance, such as dark velvety skin patches, fatty liver or PCOS.1
- You want to work out your HOMA-IR, which needs insulin and glucose from the same fasting draw.
- You’re losing weight or starting a GLP-1 drug and want to see your insulin come down.8
If you test more than once, use the same lab each time.4
How to get a fasting insulin test, and what it costs
A fasting insulin test costs $6.50 through Picardo. The Heart Health panel adds 16 more tests from the same visit for $150.90.
Heart Health panel
The panel measures insulin and fasting glucose from the same draw, so you can work out HOMA-IR. It adds HbA1c, an insulin resistance score from an advanced cholesterol test, uric acid, and kidney and liver tests. See what’s in it
Fasting insulin on its own
Only the number this page is about.
- Results in 2 to 3 days, in the app
- Physician follow-up if you want one
- Free Labcorp draw, or $75 at home
- No other fees. HSA and FSA eligible.
It’s also part of the Base Core Annual – Men, Base Core Annual – Women and Celiac / GI panels, if you want a wider checkup.
Already have a result? Ask Picardo about itQuestions people ask
What is a good fasting insulin level?
There’s no guideline target. Labcorp’s range is 2.6 to 24.9 µIU/mL.5 In a large US study of adults without diabetes, the average was about 6, and diabetes risk rose across the range.6 Because labs’ tests differ, compare your result only with others from the same lab.4
Do I need to fast for an insulin test?
Yes. Labcorp needs a fasting sample. It also asks you to stop biotin supplements at least 72 hours before, because biotin can interfere with the test.5
Can I test my insulin if I inject insulin?
Not usefully. Labcorp’s test barely detects most modern insulins, such as glargine, lispro and aspart, but it does pick up injected human insulin. Either way, it won’t show what your own pancreas makes.5
How do I convert insulin from µIU/mL to pmol/L?
Multiply by 6. A result of 10 µIU/mL is 60 pmol/L. You may see 6.945 used, but that factor is outdated.9
Can your insulin be high with normal blood sugar?
Yes. When your body resists insulin, your pancreas can make extra to keep blood sugar normal. Type 2 diabetes develops when it can no longer keep up.1
Often checked alongside
Test details
Sources
- 1 American Diabetes Association Professional Practice Committee for Diabetes. 2. Diagnosis and classification of diabetes: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1):S27–S49. doi.org/10.2337/dc26-S002
- 2 Teede HJ, Tay CT, Laven JJE, et al. Recommendations from the 2023 international evidence-based guideline for the assessment and management of polycystic ovary syndrome. J Clin Endocrinol Metab. 2023;108(10):2447–2469. doi.org/10.1210/clinem/dgad463
- 3 Styne DM, Arslanian SA, Connor EL, et al. Pediatric obesity—assessment, treatment, and prevention: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2017;102(3):709–757. doi.org/10.1210/jc.2016-2573
- 4 Rohlfing C, Petroski G, Hatten-Beck M, et al. The current status of serum insulin measurements and the need for standardization. Clin Chem Lab Med. 2025;63(12):2442–2446. doi.org/10.1515/cclm-2025-0552
- 5 Labcorp. Insulin, test 004333. Labcorp test menu. Accessed October 28, 2026. www.labcorp.com/tests/004333/insulin
- 6 Mackey RH, Mora S, Bertoni AG, et al. Lipoprotein particles and incident type 2 diabetes in the Multi-Ethnic Study of Atherosclerosis. Diabetes Care. 2015;38(4):628–636. doi.org/10.2337/dc14-0645
- 7 Poon AK, Meyer ML, Reaven G, et al. Short-term repeatability of insulin resistance indexes in older adults: the Atherosclerosis Risk in Communities Study. J Clin Endocrinol Metab. 2018;103(6):2175–2181. doi.org/10.1210/jc.2017-02437
- 8 Eli Lilly and Company. A study of tirzepatide (LY3298176) in participants with obesity or overweight (SURMOUNT-1). ClinicalTrials.gov identifier NCT04184622. Results first posted April 24, 2023. Accessed October 28, 2026. clinicaltrials.gov/study/NCT04184622
- 9 Knopp JL, Holder-Pearson L, Chase JG. Insulin units and conversion factors: a story of truth, boots, and faster half-truths. J Diabetes Sci Technol. 2019;13(3):597–600. doi.org/10.1177/1932296818805074
- 10 Xun P, Wu Y, He Q, He K. Fasting insulin concentrations and incidence of hypertension, stroke, and coronary heart disease: a meta-analysis of prospective cohort studies. Am J Clin Nutr. 2013;98(6):1543–1554. doi.org/10.3945/ajcn.113.065565
Updated 4 Nov 2026.
This is general health information, not medical advice: talk to your clinician about your results and before changing any treatment.