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Blood Test: Insulin

Reviewed by: Larissa Hirsch, MD
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What Is a Blood Test?

By taking and testing a small sample of a person’s blood, doctors can check for many kinds of diseases and conditions. Blood tests help doctors check how the body’s organs are working and see if medical treatments are helpful.

To help your child get ready for a blood test, find out if they need to fast (not eat or drink) or should stop taking medicines before the test. Explain what to expect during the test. If your child is anxious about it, work together on ways to stay calm.

What Is an Insulin Test?

This test measures the amount of insulin, the hormone that lets cells take in glucose. Glucose, a sugar that comes from food, is the body's main source of energy. 

Glucose levels in the blood rise after meals and trigger the pancreas to make insulin and release it into the blood. Without insulin, glucose can't get into the cells and it stays in the bloodstream.

With too little insulin, blood sugar is too high (hyperglycemia) and cells can't get the energy they need. With too much insulin, blood sugar is too low (hypoglycemia), causing symptoms such as sweating, trembling, and lightheadedness. Diabetes can cause the body to not make the right amount of insulin.

Why Are Insulin Tests Done?

Insulin blood tests can help doctors find the cause of hypoglycemia and other conditions related to abnormal insulin production. The test also helps them diagnose and monitor insulin resistance. Someone who is obese and has insulin resistance may go on to develop type 2 diabetes. Females with polycystic ovarian syndrome also can have insulin resistance.

Despite high blood sugar levels, insulin levels are very low in children who have type 1 diabetes.

What if I Have Questions?

If you have questions about the insulin test or what the test results mean, talk to your doctor. 

Reviewed by: Larissa Hirsch, MD
Date reviewed: September 2021