Skip to content
Home » How To Test Insulin Levels In Blood?

How To Test Insulin Levels In Blood?

How To Test Insulin Levels In Blood

Testing insulin levels in the blood is recommended by doctors for various disease conditions, such as prediabetes, diabetes, polycystic ovary disease (PCOS), etc. Let’s learn about different tests for insulin levels, the need to test insulin levels, preparation for the test, and beyond.

How to Test Insulin Level in Blood?

Before learning about different tests for insulin level measurement and the need for this test, it’s important to understand insulin, insulin resistance, and symptoms of insulin resistance.

How To Test Insulin Levels In Blood

What is insulin?

Insulin is a hormone secreted by the β-cells of the pancreas in the human body. The primary function of insulin is to regulate the glucose levels in the blood by facilitating glucose absorption from the food into the blood. The excess glucose is stored in muscles, fat, and the liver. Insulin is also involved in the metabolism of fats and proteins.

When the blood glucose levels increase after meals, β-cells secrete insulin in the blood. Insulin promotes the uptake of glucose from the blood to the cells, required for energy and normal functioning. Thus, insulin helps to reduce blood glucose levels. Excess or low levels of insulin in the blood are harmful to the body, as they could lead to serious metabolic disorders.

What is insulin resistance?

Insulin resistance is a medical condition when the cells in your body are not responding appropriately to the insulin, leading to poor glucose absorption from the blood. Poor absorption leads to an increase in blood glucose levels, signaling the pancreas to secrete more insulin, and consequently, insulin levels are also increased in the blood.

Insulin resistance can lead to diabetes and other metabolic disorders.

Symptoms of insulin resistance

It can present with the following symptoms:

  • Excessive hunger or thirst
  • Frequent urination
  • Excessive tiredness
  • Numbness or tingling sensation in extremities
  • Increased risk of infections
  • Skin problems, such as skin dryness, skin tags, etc.
  • High blood sugar levels
  • High blood insulin levels
  • High cholesterol levels
  • High blood pressure

The majority of these symptoms can be reversed with exercise and weight loss.

Tests for blood insulin levels

Tests for blood insulin levels include the following:

Fasting Insulin test: This test used to determine the level of insulin in the blood following a minimum of 8 hours of fasting. This test helps to find out abnormal levels of insulin diabetes and insulin resistance. The normal range of insulin for the fasting insulin test is 2.6 to 24.9 micro IU/mL.

Values low or higher than the range could indicate metabolic disorders or insulin resistance. In people with type 2 diabetes, insulin levels are high or normal during the initial stage of the disorder, and during the secondary stage of type 2 diabetes, insulin levels tend to get low. In people with type 1 diabetes, insulin levels are generally low.

High levels of insulin during fasting (with blood glucose <40 mg/dL) along with high levels of C-peptide and proinsulin are indicative of insulinoma.

  Test NameLevel of insulinInterpretation/Disorders
Fasting Insulin test   NormalNo disorders
LowType 2 diabetes, pancreatic cancer, Chronic pancreatitis, Hypopituitarism
HighInsulin Resistance, Insulinomas, Cushing syndrome, Fructose intolerance, Acromegaly, Obesity, Use of oral contraceptives
High or normalHypoglycemia is caused by excess insulin

In addition to the fasting insulin test, an insulin tolerance test is recommended to determine insulin sensitivity, although it’s not widely used. This test includes an intravenous (IV) infusion of insulin followed by measuring blood sugar levels and blood insulin levels. This test can be ordered in obese people or women with PCOS.

Why do you need the insulin test?

You need the insulin test for the following reasons:

  • To diagnose insulin resistance
  • To determine possible causes of low blood sugar levels (hypoglycemia)
  • To detect the possibility of insulin-producing pancreatic tumor (insulinoma)
  • To determine the requirement for additional insulin injections or other medications in people with type 2 diabetes mellitus
  • To assess the insulin production functioning of β-cells of the pancreas
  • To determine the success of a transplant of the islet cells

When to go for an insulin blood test?

You should go for an insulin blood test under the following conditions:

  • An insulin blood test usually recommended after acute or chronic symptoms of hypoglycemia. Such as palpitation, sweating, blurred vision, dizziness, confusion, excessive hunger, fainting, and loss of consciousness.
  • For monitoring insulin production in metabolic disorders such as diabetes, etc.
  • For suspected cases of insulin resistance.

How to prepare for an insulin blood test?

Preparation for an insulin blood test typically involves fasting for at least 8 hours before the test, usually overnight. In certain conditions, the doctor might go for the test when fasting is not possible, as in the case of accidents, medical emergencies, etc. In certain cases, your doctor might advise fasting for more than 8 hours.


Insulin is a naturally produced hormone in the human body that regulates blood glucose levels along with the metabolism of carbohydrates, proteins, and fats. The inability of your body to respond to insulin could lead to insulin resistance or loss of insulin sensitivity, resulting in high blood glucose levels, abnormal insulin levels, and various metabolic disorders.

An insulin test is used to measure insulin level in the blood and to assess/detect insulin resistance, hypoglycemia, insulinoma, and pancreas functioning. The insulin blood test requires 8 hours of fasting before the blood sample is collected. You might be recommended for the insulin test. If you present with symptoms of hypoglycemia, insulin resistance, diabetes, PCOS, etc.

Frequently Asked Questions (FAQ)

Are there any risks of the Insulin test?

The insulin test is quite safe and there is no major risk involved. You might experience slight pain or bruise at the site where the needle was used to withdraw the blood and these go away very quickly. In rare cases, some people with sensitive skin types might develop a hematoma (blood collection outside blood vessels) at the site of puncture. If you have any bleeding or clotting disorders, you should inform your doctor or service provider in advance for appropriate measures.

What might affect my test results?

Insulin test results can be affected by various factors such as excessive intake of carbohydrates, weight gain, lack of physical activity, or inflammatory conditions. Excess physical activity, prolonged fasting, surgeries, injuries, stress, and menstruation can also affect insulin test results.