Insulin Fasting Test

Insulin is a hormone secreted by the pancreas. It helps in the uptake of glucose from the bloodstream into the cells of our body for the production of energy. Carbohydrates from the food that we eat are broken down during digestion into simpler molecules called glucose which is absorbed into the bloodstream from our digestive system. Therefore, based on how much one eats, the insulin production by the pancreas will increase or decrease.

In the case of diabetes mellitus, there can be an issue with insulin production in the body. Depending on whether a person has Type 1 Diabetes or Type 2 Diabetes or any other disease affecting the function of the pancreas, the insulin levels in the blood can vary.

The fasting insulin test is done after fasting for 8 to 12 hours to ensure the correct measurement of insulin. When the body has not received any food to digest and process over the last 10 hours, insulin levels are expected to drop. Thus, the insulin levels should be in the normal range when the blood sample is analysed for a normal individual. Higher or lower than normal insulin levels would indicate either the pancreas not functioning optimally or some other pathological condition in the body.

Type 1 diabetes is also known as IDDM - Insulin Dependent Diabetes Mellitus. The results of the insulin fasting test provide the know-how for the management of type 1 diabetes.

Type 2 diabetes is known as NIDDM - Non-Insulin Dependent Diabetes Mellitus. One of the reasons for Type 2 diabetes is insulin resistance. When the body's cells do not respond to insulin levels, it is known as insulin resistance. This resistance causes the pancreas to produce more insulin. The insulin fasting report can assist with better diagnosis and confirmation of this condition.

Since this test directly measures the insulin levels in the blood, it is helpful for doctors to determine if the medication for diabetes needs to include insulin.

In a situation where insulin fasting test results are abnormally high, they point towards a possible tumour of the pancreas known as an insulinoma.

The insulin Fasting Test is Also Referenced as

• Insulin F
• Insulin Serum

What does the Insulin Fasting Test Detect/Measure, and who is this Prescribed for?

A fasting insulin test measures the level of insulin in the blood. This measurement is done by analysing the blood sample. The person is asked to fast before the test to determine the production of insulin from the resting state of the pancreas. This fasting ensures there is no immediate requirement from the pancreas to produce large quantities of insulin. This baseline insulin is what the fasting insulin test measures.

The measurement enables this fasting insulin test to detect insulinomas as well. Insulinoma is a pancreatic tumour. In the case of such a tumour, the pancreas produces insulin far more than the standard quantity.

The fasting insulin test is prescribed for all genders and age groups equally. One can expect to be prescribed a fasting insulin test in case of the following parameters:

• Family history of diabetes.
• Pregnancy while already suffering from Type 1 or Type 2 diabetes.
• Pregnancy with diabetes - gestational diabetes.
• Obesity or being overweight.
• Sedentary lifestyle or less active physically.
• History of high blood sugar levels posts meals.

These are all parameters that increase the risk of developing diabetes in a person.

In such cases, a fasting insulin test may be prescribed as a general check-up.

Other conditions for which fasting insulin test is prescribed are:

• Known case of Type 1 diabetes.
• Known case of Type 2 Diabetes.
• A diabetic person not responding to oral medication.
• Uncontrolled blood sugar levels.
• Gestational diabetes.
• Frequent hypoglycemic episodes

Some symptoms, if reported by a person, may warrant a prescription of an insulin fasting test from the doctor:

• Abnormally high blood sugar levels.
• Abnormal sweating, increased urination, increased thirst, increased appetite levels, Blurring of vision, palpitations.
• A previous report marks a person at risk of diabetes, i.e. Prediabetes.
• Occasional dizziness, fainting spells.
• Unexplained lethargy, and weakness.
• Dry mouth or excessive thirst.

The normal range of insulin reported in an insulin fasting test is in the range of 2.6 - 37.6 μIU/ml.

Insulin is sometimes observed below 2.6 μIU/ml.

But, if an insulin fasting test report is greater than 37.6 μIU/ml, it is a high result.

The results of the insulin fasting test can not be interpreted as a standalone result, except in the case where they are abnormally high and point towards the possibility of an insulinoma.

The insulin fasting test is used as a confirmatory test for diabetes. Therefore, the results should be compared or interpreted along with the blood sugar fasting test and other tests for diabetes.

The insulin fasting test is done by taking a blood sample. This blood sample for the insulin fasting test is drawn after 8-12 hours of fasting. This means the person giving the sample should not have any food or beverages except water for around 10 hours before the blood draw. This test is often accompanied by the Blood Sugar Fasting Test, Urine Sugar test, HBA1c for diabetes, and sometimes, the Lipid Profile Test.

Preparation before the insulin fasting test

A person needs to fast for around 8-12 hours the previous night and then give blood for testing fasting insulin levels in the morning. During the period of fasting, the person can have water. No food or beverages are allowed. Regular medication, including diabetes medication, should be continued (consult your doctor to understand the need to stop any medicine before the test)

During the fasting insulin test

There are no specific instructions during the fasting insulin test. It is a quick blood test that gets done in 5-10 minutes. The blood sample is taken from the veins of your arm.

Test Inclusions:

What Parameters Are Included?

The Insulin Fasting test includes only a straightforward blood test. It checks for the insulin level in the blood after fasting for up to 12 hours. It measures the insulin produced by the pancreas and the amount present in the blood when there is no food to break down and convert into glucose for energy. This is the only parameter to test in the fasting insulin test.

Although, for a complete diagnosis, the doctor may prescribe some other tests to be done along with this test.

Hypoglycaemia, Type 1 Diabetes, Type 2 Diabetes, Pancreatic tumours such as Insulinoma, Insulin resistance