Also Known As: Fasting Insulin, Immunoreactive Insulin, Insulin, Serum
What Is An Insulin Fasting Test?
The insulin fasting test measures the amount of insulin present in your blood serum. Insulin is a hormone generated and kept in the beta cells of your pancreas. It is produced in response to an increased blood glucose level after a meal and is very important for storing and transporting glucose in the body as the main energy source. Insulin is also responsible for transporting glucose from the blood to the cells, which in turn regulate blood glucose levels and aid in lipid metabolism.
Insulin plays a crucial role in keeping your glucose at an appropriate level. If glucose is too high or too low, it can lead to severe health problems. If the Glucose level is not normal, it is known as:
Hypoglycemia- A condition in which blood glucose levels are too low. Your body starts to send too much insulin into the blood and your body cells.
Hyperglycemia- A condition in which blood glucose levels are extremely high. It occurs when your body is unable to make enough insulin. Glucose cannot go into cells and stays in the bloodstream when it happens.
Another most common cause of abnormal glucose levels in the body is diabetes. There are two types of diabetes:
Type 1 diabetes mellitus- In this condition, your body makes very little or no insulin, which ultimately leads to hyperglycemia.
Type 2 diabetes mellitus- People with type 2 diabetes mellitus can still make insulin, but the cells in their bodies are unable to respond well to it. The cells cannot easily take adequate glucose from the blood causing insulin resistance.
What Is The Test Used For?
Your doctor or health care practitioner can ask for an insulin fasting test to:
- Diagnose and understand the cause of hypoglycemia in a patient showing relatable signs and symptoms
- To diagnose and treat insulinoma to verify the successful removal of the tumor and to monitor for the recurrence
- To check for insulin resistance
- To determine if you are type 2 Diabetes mellitus, need insulin to supplement the oral medications
- To monitor the amount of insulin by the pancreas ( Beta cells- endogenous). Along with this test, the doctor can also order a C-peptide test because your body produces insulin and C-peptide at the same rate during the conversion of proinsulin to insulin in the pancreas. This test is ordered if the doctor wants to evaluate the amount of insulin in the blood made by the body endogenously and from outside sources exogenously ( for example, insulin injections).
- To help determine and analyze the success of an islet cell transplant planned to restore your body's ability to make insulin
Why And When Do You Need An Insulin Fasting Test?
The insulin fasting test is most frequently ordered along with a blood glucose test when an individual is showing chronic or acute symptoms related to hypoglycemia or low blood glucose. The symptoms of hypoglycemia include the following:
- Extreme hunger
- Severe sweating
- Blurred vision and confusion
- Fainting ( in some cases)
- Seizure and loss of consciousness (in severe circumstances)
- Irregular heartbeat
Even though these symptoms are related to low blood glucose, they may also be present with other health conditions. Your doctor can also order this test if you are suspected of having insulin resistance with type 2 diabetes mellitus, polycystic ovarian syndrome (PCOS), metabolic syndrome, pre-diabetes, and heart diseases.
What Kind Of Sample Is Required For The Test?
During the insulin fasting test, your lab technician or health care provider will draw a blood sample from a vein in your arm. They will insert a small needle to draw out the desired amount of blood for the test. Once adequate blood is collected in the vial or test tube, the test sample will be sent to the lab. The process is simple and only takes about 5 minutes or less to complete.
Do You Need To Prepare For The Test?
As the name suggests, the insulin fasting test will require you to do a fast of at least 8 hours or more as per your doctor's recommendation. Before the test, it is also important that you discuss the list of your medications and supplements with your doctor so they can let you know about their intake for the procedure.
Are There Any Risks To This Test?
Since it is a general blood test, there is almost little to no risk associated with the procedure. You might experience slight bruising or pain at the spot where the needle was inserted, but most symptoms are mild and usually go away on their own quickly.
What Do The Test Results Mean?
This test is mainly used to test the insulin levels in the body and diagnose/ rule out the presence of insulin resistance and diabetes. This test is also a measure of hypoglycemia which is an insulin-related disorder. When your body is working ideally, the process of glucose transportation out of the blood only takes about two hours or less. When glucose stays in the blood longer than this, it can become a root cause of many chronic illnesses like heart or nerve damage and organ dysfunction.
In diabetic people, there is either lack of insulin or insulin is present but unable to do its job. It can lead to insulin resistance where blood glucose levels are abnormally and dangerously high.
Elevated insulin levels are often present in:
- Insulin resistance in people with type 2 diabetes mellitus, metabolic syndrome, and acanthosis nigricans
- Cushing syndrome
- The presence of tumors called insulinomas
- Use of certain drugs like levodopa, corticosteroids, and contraceptives
- Galactose and fructose intolerance
Low insulin levels can be seen with:
- Pancreatic diseases including chronic pancreatitis, pancreatic cancer, and cystic fibrosis
- Hyperglycemia or high blood sugar
Here, it is essential to note that the glucose and insulin in your body work together, so your doctor or health care provider might need to compare your results with another blood glucose test to make an appropriate diagnosis.
Related Tests: Glucose Plasma Test, Glucose Blood Test, Glucose Tolerance Test (GTT), Insulin Autoantibodies (IAA) (Endocrine Sciences), C-Peptide Serum Test, Glucose Serum Test, Insulin Free, and Total Blood Test, Insulin Response Blood Test
Frequently ordered together
Glucose 2 Hour Post Prandial
Glucose Tolerance Test GTT
Glucose Fasting & Postprandial-2 hour HR
Insulin 2 Specimens
GLUCOSE POSTPRANDIAL 1 HR
Glucose Fasting and Gestational 135 Cutoff
Glucose Plasma with Reflex
Glucose Postprandial PP 2-Hour (75g)
Glucose Tolerance Test Gestational-4 Specimens (100g)
Glucose Gestational Screen 50g 135 Cutoff
Glucose Tolerance Test Gestational 3 Specimens (75g)
Glucose Gestational Screen 50g 140 Cutoff
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