You know that insulin you inject every day? It's very important stuff. Read on to learn why.

It's true: Insulin is the thing for everybody who owns a body . . . which runs on energy . . . which comes from blood sugar . . . which won't give you energy unless insulin is there to help it.

Special cells in the body's pancreas are the only ones that produce insulin for you. But diabetes really messes with the pancreas, until there's no way those cells can make insulin anymore. So, if you have diabetes, you have to get your insulin from the outside rather than the inside.

Where It Comes From

Just where "outside" does the stuff come from? What exactly is in a bottle of insulin? And why inject it?

Let's answer that last question first. You have to inject your insulin, instead of just swallowing it, because it's a protein. Your stomach and intestines really like to digest protein — they do it every time you eat things like peanut butter, eggs, and meat. But you don't want to digest insulin, at least not until it's done its work controlling your blood sugar. By injecting it into your muscle, your stomach doesn't get hold of it, and the insulin is able to work in your bloodstream.

Now, where does the insulin come from? The animal world has been a great friend to us when it comes to providing insulin. The first insulin ever identified by scientists, 75 years ago, came from a dog. Today, the insulin you inject every day might have come from a pig or a cow. (Don't worry -- it's cleaned up very well before it's bottled.)

More likely, you use a type of insulin called "human" insulin. This is not exactly like the insulin you would make in your pancreas, but it's close. And guess what: It comes from . . . bacteria! About 25 years ago, biologists found that they could "teach" bacteria growing in a lab dish to make human insulin. The bacteria made large amounts of it, almost identical to the real thing. Today many people use insulin produced in this way. Your parents, doctor, nurse, or pharmacist will be able to tell you where your insulin comes from, so ask them!

What the Bottle Tells You

Now take a look at your bottles of insulin (ask for help if you don't usually handle them yourself). Besides

insulin, they contain very pure water. But did you know that substances such as zinc may have been added? These allow you to control how fast and how long the insulin will work.

Look at the labels on the bottles. You'll see some of the following big letters describing the type of insulin. Here's what they mean:

• R or S  — This is a short-acting insulin. It starts controlling blood sugar fast (within 1/2 hour) but stops working sooner than other types of insulin. 
• N or L — This is intermediate-acting insulin. It starts working within 1 hour, works hardest in 6 to 10 hours, and lasts about a day. It's milky, not clear, because a substance has been added to slow it down. You need to mix it (by rolling, not shaking) before you use it. 
• U — This is the longest-acting insulin. It starts working in 3 to 6 hours and lasts for more than a day. It's milky looking, too.

You might notice that your labels say —70/30— or —50/50— instead. These bottles have a mixture of R and N types of insulin, to give you even better control over timing. Your doctor decides what kinds of insulin are best for you, so don't go changing them unless the doctor or nurse says to.

Why Your Dose May Change

Oh, you may have noticed that as your body grows, you need more and more insulin to control blood sugar. Somebody who's 18 might be taking 4 times more insulin than when they were 8.
The only way you and your doctor will know when and how much to increase insulin is by the results of your blood sugar tests. They're almost as important as taking insulin.

So, be in the know and control as you grow!