Insulin

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Formal name: Insulin

At a Glance

Why Get Tested?

To help evaluate insulin production in diabetes, diagnose an insulinoma (insulin-producing tumour), and to help determine the cause of low blood glucose (hypoglycaemia)

When to Get Tested?

If you have hypoglycaemia, if you have symptoms suggesting insulin is being inappropriately produced by your body, and sometimes if you have diabetes and your doctor wants to monitor your insulin production

Sample Required?

A blood sample drawn from a vein in your arm

The Test Sample

What is being tested?

Insulin is a hormone that is produced by the pancreas. Insulin helps to control blood glucose levels and plays a role in controlling the levels of carbohydrates and fats stored in the body.

When blood glucose levels rise after a meal insulin is released by the pancreas. The insulin allows glucose to be taken up by the body's cells, especially muscle cells, where is it is used for energy production. Insulin then signals to the liver to store the remaining excess blood glucose as carbohydrates and fat.

Humans need insulin on a daily basis to survive. Without insulin, glucose cannot leave the bloodstream and enter most of the body's cells. The cells starve and blood glucose levels rise to dangerous levels. Eventually, very high glucose levels lead to a life-threatening condition called a diabetic coma.

People with type 1 diabetes produce very little insulin and must take insulin injections several times a day. People with type 2 diabetes usually can produce insulin and their insulin levels may even be high, but the body is not able to respond normally to the insulin. This is known as insulin resistance. People with type 2 diabetes may need oral medications that increase their body's cells response to insulin or that stimulate their body to produce more insulin. In some cases type 2 diabetics may also need to take insulin injections to keep their blood glucose levels normal.

Insulin and glucose levels must be in balance. An excess amount of insulin in the blood is known as 'hyperinsulinaemia'. If this is caused by an insulin-producing tumour in the pancreas (a so-called 'insulinoma') or due to an excess amount of injected insulin, it can be very dangerous. It causes hypoglycaemia (low blood glucose levels), which can lead to sweating, rapid heart beat, hunger, confusion, visual problems and seizures. Since the brain is totally dependent on blood glucose as an energy source, glucose deprivation due to hyperinsulinaemia can lead to death.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

The Test

Common Questions

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.