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Insulin in Blood

What is an insulin in blood test?

This test measures the amount of insulin in your blood. Insulin is a hormone that helps move blood sugar, known as glucose, from your bloodstream into your cells. Glucose comes from the foods you eat and drink. It is your body's main source of energy.

Insulin plays a key role in keeping glucose at the right levels. If glucose levels are too high or too low, it can cause serious health problems. Glucose levels that are not normal are known as:

  • Hyperglycemia, blood glucose levels that are too high. It happens when your body doesn't make enough insulin. If there's not enough insulin, glucose can't get into your cells. It stays in the bloodstream instead.
  • Hypoglycemia, blood glucose levels that are too low. If your body sends too much insulin into the blood, too much glucose will go into your cells. This leaves less in the bloodstream.

Diabetes is the most common cause of abnormal glucose levels. There are two types of diabetes.

  • Type 1 Diabetes. If you have type 1 diabetes, your body makes little or no insulin at all. This can cause hyperglycemia.
  • Type 2 Diabetes. If you have type 2 diabetes, your body may still be able to make insulin, but the cells in your body don't respond well to insulin and can't easily take up enough glucose from your blood. This is called insulin resistance.

Insulin resistance often develops before type 2 diabetes. At first, insulin resistance causes the body to make extra insulin, to make up for ineffective insulin. Extra insulin in the bloodstream can cause hypoglycemia. But insulin resistance tends to get worse over time. Eventually, it decreases your body's ability to make insulin. As insulin levels drop, blood sugar levels rise. If levels don't return to normal, you may get type 2 diabetes.

Other names: fasting insulin, insulin serum, total and free insulin

What is it used for?

An insulin in blood test is most often used to:

  • Find out the cause of hypoglycemia (low blood sugar)
  • Diagnose or monitor insulin resistance
  • Monitor the condition of people with type 2 diabetes
  • Find out if there is a type of tumor on the pancreas, known as an insulinoma. If the tumor has been removed, the test may be used to see if it has been done successfully.

An insulin in blood test is sometimes used along with other tests to help diagnose and monitor type 1 diabetes. These other tests may include glucose and hemoglobin AIC testing.

Why do I need an insulin in blood test?

You may need an insulin in blood test if you have symptoms of hypoglycemia (low blood sugar). These include:

You may also need this test if other tests, such as a blood glucose test, show you have low blood sugar.

What happens during an insulin in blood test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out.

Will I need to do anything to prepare for the test?

You will probably need to fast (not eat or drink) for eight hours before the test.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

If your insulin levels were too high, it may mean you have:

  • Type 2 diabetes
  • Insulin resistance
  • Hypoglycemia
  • Cushing's syndrome, a disorder of the adrenal glands. Adrenal glands make hormones that help the body break down fat and protein.
  • An insulinoma (pancreatic tumor)

If insulin levels were too low, it may mean you have:

  • Hyperglycemia (high blood sugar)
  • Type 1 diabetes
  • Pancreatitis, an inflammation of the pancreas

If you have questions about your results, talk to your health care provider.

Is there anything else I should know about an insulin in blood test?

Insulin and glucose work together. So your health care provider may compare your insulin in blood results with blood glucose test results before making a diagnosis.

References

  1. American Diabetes Association [Internet]. Arlington (VA): American Diabetes Association; c1995–2019. Hypoglycemia (Low Blood Glucose) [updated 2019 Feb 11; cited 2019 Feb 20]; [about 3 screens]. Available from: http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/hypoglycemia-low-blood.html
  2. American Diabetes Association [Internet]. Arlington (VA): American Diabetes Association; c1995–2019. Insulin Basics [updated 2015 Jul 16; cited 2019 Feb 20]; [about 4 screens]. Available from: http://www.diabetes.org/living-with-diabetes/treatment-and-care/medication/insulin/insulin-basics.html
  3. Cleveland Clinic [Internet]. Cleveland (OH): Cleveland Clinic; c2019. Diabetes: Glossary [cited 2019 Feb 20]; [about 3 screens]. Available from: https://my.clevelandclinic.org/health/articles/9829-diabetes-glossary
  4. Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Insulin; 344 p.
  5. Johns Hopkins Medicine [Internet]. The Johns Hopkins University; c2019. Health Library: Diabetes Mellitus [cited 2019 Feb 20]; [about 3 screens]. Available from: https://www.hopkinsmedicine.org/healthlibrary/conditions/adult/pediatrics/diabetes_in_children_22,diabetesmellitus
  6. Johns Hopkins Medicine [Internet]. The Johns Hopkins University; c2019. Health Library: Insulinoma [cited 2019 Feb 20]; [about 3 screens]. Available from: https://www.hopkinsmedicine.org/healthlibrary/conditions/adult/digestive_disorders/insulinoma_134,219
  7. Kids Health from Nemours [Internet]. Jacksonville (FL): The Nemours Foundation; c1995–2019. Blood Test: Insulin [cited 2019 Feb 20]; [about 3 screens]. Available from: https://kidshealth.org/en/parents/test-insulin.html
  8. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Cushing Syndrome [updated 2017 Nov 29; cited 2019 Feb 20]; [about 2 screens]. Available from: https://labtestsonline.org/conditions/cushing-syndrome
  9. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Insulin [updated 2018 Dec 18; cited 2019 Feb 20]; [about 2 screens]. Available from: https://labtestsonline.org/tests/insulin
  10. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Pancreatitis [updated 2017 Nov 28; cited 2019 Feb 20]; [about 2 screens]. Available from: https://labtestsonline.org/conditions/pancreatitis
  11. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2019. Type 1 diabetes: Diagnosis and treatment; 2017 Aug 7 [cited 2019 Feb 20]; [about 4 screens]. Available from: https://www.mayoclinic.org/diseases-conditions/type-1-diabetes/diagnosis-treatment/drc-20353017
  12. Mayo Clinic Laboratories [Internet]. Mayo Foundation for Medical Education and Research; c1995–2019. Test ID: INS: Insulin, Serum: Clinical and Interpretive [cited 2019 Feb 20]; [about 4 screens]. Available from: https://www.mayocliniclabs.com/test-catalog/Clinical+and+Interpretive/8664
  13. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co., Inc.; c2019. Diabetes Mellitus (DM) [cited 2019 Feb 20]; [about 2 screens]. Available from: http://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/diabetes-mellitus-dm-and-disorders-of-blood-sugar-metabolism/diabetes-mellitus-dm
  14. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests [cited 2019 Feb 20]; [about 3 screens]. Available from: https://www.nhlbi.nih.gov/health-topics/blood-tests
  15. National Institute of Diabetes and Digestive and Kidney Diseases [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Insulin Resistance and Prediabetes [cited 2019 Feb 20]; [about 5 screens]. Available from: https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance
  16. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2019. Health Encyclopedia: Total and Free Insulin (Blood) [cited 2019 Feb 20]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=insulin_total_free
  17. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2019. Insulin Resistance: Topic Overview [updated 2017 Dec 7; cited 2019 Feb 20]; [about 2 screens]. Available from: https://www.uwhealth.org/health/topic/special/insulin-resistance/hw132628.html

The medical information provided is for informational purposes only, and is not to be used as a substitute for professional medical advice, diagnosis or treatment. Please contact your health care provider with questions you may have regarding medical conditions or the interpretation of test results.

In the event of a medical emergency, call 911 immediately.