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How Insulin Works

Insulin in Your Body

How do our bodies make and use insulin? What happens when insulin can't do its job? Take a trip inside the body in this fascinating animated video "Insulin in Your Body" and see for yourself.

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Insulin in Your Body

What Are Insulin and Glucose?
When you hear the word insulin, you may think of a drug taken by people who have diabetes.

While this is true, what you may not know is that insulin is one of the many hormones created in the human body.

Insulin is important to the body. It allows blood sugar (or glucose) to get into cells to provide them with energy.

When you eat, your body breaks down food into glucose in your small intestine.

This is your body’s source of energy for everything it does, from working and thinking to exercising and healing.

Glucose travels through your bloodstream, looking for individual cells that need energy.

For glucose to get into the cells, it requires insulin.

Insulin is the key that unlocks cells for glucose to enter and deliver energy.

When insulin arrives, it signals the cell to activate glucose transporters.

These transporters pull glucose through cell walls.

When glucose moves into the cell, it delivers energy!

When Your Body Doesn’t Make Enough Insulin
Insulin is normally produced in the pancreas by specialized cells called beta cells.

When glucose enters your bloodstream, the pancreas matches it with the right amount of insulin to move glucose into your cells. In people with diabetes, this process doesn’t work as it should.

In type 1 diabetes, scientists believe the body’s immune system mistakenly attacks and destroys beta cells in the pancreas. A person with type 1 diabetes loses the ability to produce insulin.

In type 2 diabetes, the pancreas is not producing enough insulin to meet the body’s needs.

Over time, the amount of insulin typically becomes less and less.

When Your Body Resists Insulin
In some type 2 diabetes patients, cells build up a resistance to insulin. Even though there may be insulin in the bloodstream, it is not enough to unlock cells to allow glucose to enter.

As a result, it takes more insulin to find the right key to unlock the cell for glucose. This makes it more difficult for cells to get the energy they need.

Why Diabetes Leads to High Blood Sugar
When glucose can’t get into cells – either because there isn’t enough insulin or because the body is resisting it...

...glucose begins to build up in the bloodstream.

As a result, all that energy is wasted. It does not get to cells where it is needed. Without glucose in your cells, they lack the energy they require to keep your body working.

To keep glucose from building up in the blood stream, an external supply of insulin may be needed.

How Injected Insulin Works
Because people with type 1 diabetes can’t produce their own insulin, they must inject insulin several times every day or receive insulin through an insulin pump. Many people with type 2 diabetes take insulin too.

Injected insulin acts on glucose in a similar way to insulin the body would produce if it could. Like the body’s insulin, injected insulin helps reduce the amount of glucose in the bloodstream by getting it into cells where it is needed for energy.

Talk to your doctor to see if insulin might be right for you. Use our discussion guide to help lead that conversation.

Important Safety Information about Insulin:
The most common side effect of insulin is low blood sugar. Some people may experience symptoms such as shaking, sweating, fast heartbeat, and blurred vision, while some experience no symptoms at all. That's why it's important to check your blood sugar often.

Different types of insulin

Everyone has different needs. So there are different types of insulin. What's the best choice for your lifestyle and schedule? Talk to your doctor. He or she can help you find the insulin treatment that's right for you.

Insulin Type How it works
Rapid-acting Starts to work in about 5 minutes and continues to work for up to 5 hours
Regular or short-acting Begins to work within 30 minutes and continues working for 5 to 8 hours
Intermediate-acting Usually begins to work in 2 to 4 hours and continues to work for about 10 to 16 hours
Long-acting Begins to work in 2 to 4 hours and can work for 24 hours
Premix A mixture of two insulins in predetermined proportions. It combines an intermediate-acting insulin and a rapid- or short-acting insulin in one dose

Exercise, diet, and other diabetes treatments are all part of diabetes therapy. Speak with your healthcare professional to understand the appropriate treatment for controlling your blood sugar.

Important Safety Information About Insulin

The most common side effect of insulin is low blood sugar. Some people may experience symptoms such as shaking, sweating, fast heartbeat, and blurred vision, while some experience no symptoms at all. That's why it's important to check your blood sugar often.

Insulin Frequently Asked Questions

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The health information contained herein is provided for general educational purposes only. Your healthcare professional is the single best source of information regarding your health. Please consult your healthcare professional if you have any questions about your health or treatment.