Quick answer
The Serum Insulin Test (Fasting) costs ₹700 at Live Line Health Care. Measures insulin after an overnight fast, which doctors read with fasting glucose to look for insulin resistance, as in PCOS, fatty liver and prediabetes. 8–12 hours overnight fast (water allowed). Tell staff if you use insulin injections or take biotin.
Also known as: Serum Insulin, Fasting Insulin, Insulin Level, Insulin Fasting, Insulin Resistance Test, HOMA-IR Test
What is the Fasting Insulin Test?
The fasting serum insulin test measures how much insulin is in your blood after an overnight fast. Insulin is a hormone made by the pancreas that lets your cells take in glucose. In insulin resistance, the cells respond poorly, so the pancreas makes more and more insulin to keep sugar normal. For years, a person may have a normal fasting sugar while their insulin runs high. This test can show that hidden strain before blood sugar rises.
Doctors rarely read insulin alone. They combine it with a fasting glucose taken at the same time to calculate HOMA-IR, a simple estimate of insulin resistance. It is commonly ordered in PCOS, fatty liver, obesity, prediabetes and acanthosis nigricans, the dark velvety skin on the neck often linked with insulin resistance. It can also help in the rare case of repeated low sugar without diabetes treatment. It is not a diagnostic test for diabetes, which relies on fasting sugar, HbA1c and the glucose tolerance test. If you inject insulin, this test measures that insulin too, so a C-peptide test may suit you better.
What it measures: The concentration of insulin in your blood after an 8 to 12 hour fast.
Parameters included (1)
- Fasting Serum Insulin (µIU/mL)
Why is this test done?
- Looking for insulin resistance in PCOS, fatty liver or obesity
- Calculating HOMA-IR along with fasting glucose
- Assessing dark velvety skin patches (acanthosis nigricans)
- Investigating repeated low blood sugar in someone not treated for diabetes
- Helping a doctor decide on lifestyle or medicine plans in prediabetes
When should you get tested?
- Weight gain around the waist that is hard to lose
- Irregular periods, acne or excess facial hair, as in PCOS
- Dark, thick skin on the neck, armpits or groin
- Fatty liver on an ultrasound
- Shakiness, sweating or confusion that improves with food
How to prepare for the Fasting Insulin Test
- 1Fast for 8 to 12 hours overnight. Only plain water is allowed.
- 2Book a fasting blood sugar at the same time, as most doctors need both to calculate HOMA-IR.
- 3Tell staff if you use insulin injections, metformin, steroids or other diabetes or hormone medicines. Do not change them for this test without your doctor's advice.
- 4Stop biotin supplements for at least 2 days if your doctor agrees, since biotin can interfere with some insulin assays.
Fasting Insulin Test normal range
| Parameter | Typical reference range |
|---|---|
| Fasting insulin | About 2–25 µIU/mLdepends heavily on the assay; use the range on your report |
| HOMA-IR (calculated) | Below about 2.0–2.5 is usually considered normalfasting insulin (µIU/mL) × fasting glucose (mg/dL) ÷ 405 |
Insulin assays differ a lot, so there is no single agreed normal range or HOMA-IR cut-off. Results are most useful when compared over time at the same lab. Ranges are typical adult values and vary between labs, age and sex. Always use the range printed on your report and discuss results with your doctor.
Understanding your results
- A high fasting insulin with normal sugar suggests insulin resistance. It often improves with weight loss, regular exercise and diet changes, and your doctor may suggest medicines in some cases.
- A high HOMA-IR in PCOS or fatty liver supports insulin resistance as a driver of the condition, which can guide treatment.
- A low fasting insulin with high sugar may suggest the pancreas is not making enough insulin, as in type 1 or long-standing type 2 diabetes. A C-peptide test may follow.
- A high insulin level during an episode of low blood sugar, in someone not on diabetes medicine, needs specialist evaluation, as rare insulin-producing tumours can cause this.
Health packages that include this test
The Fasting Insulin Test is included in these full body checkups:
Fasting Insulin Test – FAQs
What is the price of the Fasting Insulin Test?
The Serum Insulin Test (Fasting) costs ₹700 at Live Line Health Care, at all 45 centres and for home sample collection.
What is HOMA-IR and how is it calculated?
HOMA-IR is an estimate of insulin resistance. Multiply fasting insulin in µIU/mL by fasting glucose in mg/dL and divide by 405. For example, insulin of 10 with glucose of 90 gives about 2.2. Many doctors take values above about 2.5 as suggesting insulin resistance, though cut-offs vary.
Is fasting insulin a test for diabetes?
No. Diabetes is diagnosed with fasting sugar, HbA1c or the glucose tolerance test. Fasting insulin shows how hard your pancreas is working to keep sugar normal, which helps your doctor understand insulin resistance. It is often used before diabetes develops, or to explain conditions like PCOS.
Why is insulin tested in PCOS?
Many women with PCOS have insulin resistance, even when they are not overweight. High insulin can increase male-type hormones, which worsens irregular periods, acne and hair growth. Knowing this helps your doctor choose between lifestyle changes and medicines such as metformin. Not every woman with PCOS needs this test.
Can I take this test if I use insulin injections?
The test will measure the insulin you injected along with your own, so it cannot show how much your pancreas makes. Doctors usually prefer a C-peptide test in this situation. Please do not skip insulin for a test unless your doctor has specifically told you to.
What is the difference between fasting insulin and C-peptide?
Both reflect insulin production. Insulin and C-peptide are released together from the pancreas, but C-peptide stays in the blood longer and is not affected by injected insulin. Fasting insulin is mainly used for insulin resistance, while C-peptide is used to judge the pancreas's own output in people on insulin.
Can fasting insulin go down with lifestyle changes?
Often yes. Losing weight, especially around the waist, regular physical activity and cutting refined carbohydrates and sugary drinks can improve insulin resistance over a few months. Your doctor may repeat the test, along with fasting glucose, to see the trend.
Where can I get the Fasting Insulin Test done?
At any of our 45 Live Line Health Care centres in 40 cities across Andhra Pradesh and Telangana, including Hyderabad, Visakhapatnam, Warangal, Kakinada and Nellore, or book home sample collection.
Medical disclaimer: This information is for general awareness only and is not a substitute for professional medical advice. Please consult a qualified doctor to interpret your results and before starting or changing any treatment.