Maybe you spend your after-school hours shooting free throws on the basketball court. Or perhaps you devote your free time to gaming. One way to tell if that practice is paying off is to keep track of your progress over time — whether it's your points-per-game average or your highest score ever.

A teen with diabetes does the same thing. To keep diabetes under control, stay healthy, and prevent future problems, you have to keep blood sugar levels in a healthy range. To do that, you need to check and track those levels regularly.

Why Should I Check?

Keeping an eye on blood sugar levels has many benefits. For example, testing your blood sugar levels before and after meals helps you see how eating certain foods affects those levels. Knowing this can help you adjust your food choices.

Exercise also can make your blood sugar levels fluctuate, so test them regularly when you're active. This way you can tell whether your dose of diabetes medicine should be adjusted as you step up your physical activity.

And because being sick can mess up how much diabetes medicine your body needs, know your blood sugar levels when you're feeling ill. This can help you and your doctor to decide if you should use less or more medicine, depending on your diabetes management plan.

If you manage your diabetes on your own most of the time, checking blood sugar levels also helps reassure your parents that you're taking care of yourself.

When Should I Check?

The number of times you should test your blood sugar levels each day — and when you should test — will depend on lots of different things. It might even change from day to day. In general, most people with diabetes test their blood sugar levels before breakfast, before lunch, before dinner, and again at bedtime.

You may need to check blood sugar levels more often when you're sick or when changes have been made to your medication doses or schedule. You also may need to check more often if you suddenly become more active, like after you join a sports team at school.

People who use an insulin pump or who follow a plan to control blood sugar levels very closely also need to check their blood sugar levels more frequently. Your diabetes health care team will help you decide how often and when you should check.

Sometimes, blood sugar levels must be checked in the middle of the night — for instance, by people who are having problems with hypoglycemia symptoms during the night. And those who have just been diagnosed with diabetes may need more frequent blood sugar level tests to get a feel for how certain doses of insulin or other diabetes medicines affect their blood sugar levels.

How Does It Work?

You can test blood sugar levels at home using a blood glucose meter, which is a computerized device that measures the amount of glucose in a sample of your blood and displays it on a screen.

To get a sample of your blood, a small needle called a lancet is used to poke the skin (usually on a finger or on your forearm) to get one drop of blood. The drop is placed on a testing strip that goes into the glucose meter, and the blood glucose reading appears on a screen within a few seconds.

When you're first diagnosed with diabetes, your mom or dad may help you test your blood sugar levels and keep track of the results. As you get older, though, you'll learn how to use the glucose meter and monitor your blood sugar levels on your own. If you have any questions about using or taking care of your glucose meter, ask a member of your diabetes health care team.

How do you know which blood glucose meter to use? When you and your parents are choosing a glucose meter, you might want to consider:

• Cost. Although most insurance plans cover the cost of glucose meters and test strips, they may only cover certain brands, and they may limit the number of test strips they pay for (and test strips are the most expensive part of monitoring blood sugar levels).
• Size. Chances are you'll be using the glucose meter on the go, so you might want one that's light, portable, and easy to fit into your backpack or bag (and that still leaves room for your cell phone, PDA, or other stuff you carry).
• Speed. Glucose meters vary in how fast they provide the results of your test, but most don't take more than a few seconds. If a very quick result is something you think you need, consider the meter's speed.
• Added features. Some glucose meters let you input information in addition to your blood sugar test results, like your food intake and daily exercise. If you like to keep track of your results on a computer or you email your doctor or diabetes health care team your blood sugar readings regularly, a glucose meter that syncs with a personal computer can be handy.

Newer technologies are making it easier and less painful to keep track of diabetes. Adjustable lancets can make finger poking less painful by changing the depth to which the needle enters the skin, and certain meters can use blood drawn from a forearm or other body parts that are less sensitive than a fingertip for some people. Your diabetes health care team will help you choose the best type of equipment for you.

In some cases, your doctor may want to get an even more detailed look at how your blood sugar levels change throughout the day and night. Wearable devices that measure blood sugar levels every 5 minutes are available. Then a computer printout of your blood sugar profile can be downloaded for you, your parents, and your doctor to evaluate.

What Other Tests Can Help Me Keep Track?

Using a glucose meter can help you check your blood sugar levels, but other tests can help you know how well you're controlling your diabetes too.

The glycosylated hemoglobin test (also known as the hemoglobin A1c or HbA1c test) will tell you how you've been controlling your blood sugar levels over the past few months. It's usually done during regular visits with your diabetes health care team.

Hemoglobin is the substance inside red blood cells that carries oxygen to the cells of the body. The higher the glucose level in the blood, the more the glucose sticks to the hemoglobin. And once hemoglobin picks up glucose, the glucose stays on it for the life of the red blood cell, which is about 2 to 3 months.

The most commonly measured type of hemoglobin in the blood that has glucose attached to it is called HbA1c. In general, the lower your HbA1c, the better you've been controlling your blood sugar levels over the last 2 to 3 months. Having lower HbA1c levels may make it less likely that you'll develop long-term diabetes problems.

Ketones are something else you'll need to check for sometimes. Ketones are chemicals that show up in the urine and blood after the body breaks down fat for energy. The body will break down fat when it can't use glucose. This can happen when you haven't taken enough insulin to help the glucose get into the cells, or when you haven't eaten enough to provide glucose for energy (like when you're sick and have no appetite).

Having lots of ketones in your body can put you at risk for a major diabetes emergency called diabetic ketoacidosis that can make you very sick. So it's important that you check for ketones whenever necessary, before they build up too much in your body.

Your diabetes health care team will let you know how and when to test for ketones and teach you how the results relate to your overall diabetes treatment.

How Do I Keep Track?

Even though blood glucose meters can help you track your blood sugar test results, it's still a good idea to write down the results. This makes it easier for you and your diabetes health care team to see patterns and trends in your blood sugar levels.

Writing down all your results in a log book or journal can help. If you prefer, you can even download special programs that allow you to track your blood sugar readings on your PDA or laptop. You might need to record other information too, such as what you were eating or how active you were. This information will help you learn more about how certain situations — like eating or exercising — affect your diabetes control.

Ultimately, the more information you, your parents, and your diabetes health team have, the easier it is to keep your blood sugar levels on the right track.

Reviewed by: Steven Dowshen, MD
Date reviewed: October 2010