Diabetes: Checking your blood sugar

Because you have diabetes, you need to know when your blood sugar level is outside the target range for your body. Fortunately, you can see what your blood sugar level is anywhere and anytime by using a home blood sugar meter (blood glucose meter). Using the meter, you can find out what your blood sugar level is within a minute or two.

Knowing your blood sugar level helps you treat low or high blood sugar before it becomes an emergency. It also helps you know how exercise and food affect your blood sugar and how much short-acting insulin (if you take insulin) to take. Most importantly, it helps you feel more in control as you manage life with diabetes.

Three keys to success in monitoring your blood sugar anywhere are:

• Keeping your meter and supplies with you at all times so that you always have them when you need them.
• Making it a habit to check your blood sugar level by building it into your routine.
• Checking your blood sugar meter's accuracy when you visit your doctor by comparing your results with your doctor's results.

 What is home blood sugar monitoring?
 Why monitor your blood sugar?
 How to test your blood sugar
 Where to go from here

More information about diabetes can be found in these topics:

• Type 1 Diabetes
• Type 1 Diabetes: Recently Diagnosed
• Type 1 Diabetes: Living With the Disease
• Type 1 Diabetes: Children Living With the Disease
• Type 1 Diabetes: Living With Complications
• Type 2 Diabetes
• Type 2 Diabetes: Recently Diagnosed
• Type 2 Diabetes: Living With the Disease
• Type 2 Diabetes in Children
• Type 2 Diabetes: Living With Complications
• Gestational Diabetes

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Your doctor will most likely take a sample of blood from a vein to test your blood sugar level in his or her office or lab every 3 to 4 months. The blood sample is used for two tests: 1) to check your blood sugar level at the time of the test (blood glucose test), and 2) to measure how well your blood sugar has stayed within your target range over the past 2 to 3 months (hemoglobin A1c test or a similar test called glycohemoglobin). You may not get the results from these tests for a few hours or even a few days.

Because you have diabetes, you need to know what your blood sugar level is every day. Many years ago, the only way people with diabetes could check on the control of their diabetes was by testing their urine for sugar. Urine testing is not an accurate way to test your blood sugar level and is not recommended.

You can check blood sugar level anytime and anywhere by using a home blood sugar meter. This is often referred to as home blood sugar monitoring or self-testing. Your doctor may want you to check your blood sugar level several times a day, especially if you take insulin.

To test your blood sugar level using a blood sugar meter, prick the side of your fingertip with a small needle (lancet) to collect a drop of blood. Some blood sugar sampling devices allow you to prick other sites on your body, such as your forearm. Place the drop of blood on a special test strip inserted into your meter. (For some meters, the blood is put on the test strip before it is put in the meter.) Within a minute or less, the meter shows the results of your test. See a picture series of how to test your blood sugar at home.

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Monitoring your blood sugar level takes the guesswork out of your daily diabetes care. Testing your blood sugar at home helps you know:

• When your blood sugar is low. Low blood sugar can lead to an emergency. If your blood sugar drops just below the level that is safe for your body and you quickly eat something containing sugar, your blood sugar will rise and you may prevent an emergency.
• When your blood sugar is high. Over time, high blood sugar levels cause permanent damage to the eyes, heart, kidneys, blood vessels, and nerves. If you are pregnant, high blood sugar levels may cause problems for you and your baby. Low blood sugar levels are even more dangerous for your fetus.
• What your blood sugar level is before a meal. If you take short-acting insulin, you can use these results to determine how much insulin to take.
• How different types of food affect your blood sugar.
• How exercise affects your blood sugar. Exercise usually lowers your blood sugar level.
• What your blood sugar is when you are ill. Severe illness or stress usually causes higher-than-normal blood sugar levels.
• When your medicine for diabetes (insulin) may need adjusting. If your blood sugar levels remain high over a period of time or you have frequent low blood sugar, your medicine for diabetes may need adjusting. Talk to your doctor about this.

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Monitoring your blood sugar level at home takes the guesswork out of your daily diabetes care. You will know what your blood sugar level is at the time of testing. Here is a simple way to get started.

Get organized

Before you start testing your blood sugar:

• Talk with your doctor about how often and when you should test your blood sugar. Record this information on the blood sugar testing times form(What is a PDF document?).
• Link testing your blood sugar with other daily activities, such as preparing breakfast. This will help you establish the habit of self-testing.
• Use the list of supplies to gather the things you need to test your blood sugar. Keep your supplies together so that you can do a test quickly if necessary.
• Check your equipment before doing each test.
  • Check the expiration date on your testing strips. If you use expired test strips, you may not get accurate results.
  • Make sure the code numbers on the testing strips bottle match the numbers on your meter. If the numbers do not match, follow the directions that come with your meter for changing the code numbers.
• The first time you use a meter, and every time you switch meters, check the accuracy of your meter's results. Use the sugar control solution that is made by your meter's manufacturer. Follow the directions that came with your meter for using the control solution properly.
• At regular intervals, properly care for your equipment. Put a copy of the care of blood sugar supplies with your bag or kit as a reminder.

Do the test

Some people with diabetes test their blood sugar rarely or not at all. Other people—such as pregnant women—test it several times a day. The more often you test your blood sugar, the more you will know about how well your treatment is keeping your blood sugar levels within a target range.

Follow these steps when testing your blood sugar:

1. Wash your hands with warm, soapy water, and dry them well with a clean towel.
2. Put a clean needle (lancet) in the lancet device. The lancet device is a pen-sized holder for the lancet. It holds and positions the lancet and controls how deeply the lancet goes into your skin.
3. Get a test strip from your bottle of testing strips. Put the lid back on the bottle immediately to prevent moisture from affecting the other strips.
4. Get your blood sugar meter ready. Follow the manufacturer's instructions for your specific meter.
5. Use the lancet device to stick the side of your fingertip with the lancet. Some devices and blood sugar meters allow blood testing on other parts of the body, such as the forearm. Be sure you know where your device can be used.
6. Put a drop of blood on the correct spot of the test strip, covering the test area well.
7. Using a clean cotton ball, stop the bleeding by applying pressure to the place you stuck.
8. Wait for the results. Most meters take only a few seconds to give you the results.

Record the results

Recording your blood sugar results is very important. Your doctor will use your record to see how often your blood sugar levels are in your target range. This information lets your doctor know if your medicine (insulin or pills) needs adjusting. Be sure to take your record with you on each visit to your doctor or diabetes educator.

To record your results, you can:

• Get printed blood sugar logs from companies that make diabetic medicines and supplies. Or use this home blood sugar diary(What is a PDF document?).
• Make a blood sugar log in a notebook. You can record other information in the log or notebook, such as insulin doses, your exercise, and food you have eaten.
• Use your blood sugar meter, if it is capable. Some blood sugar meters can store from 10 to more than 100 blood sugar results. Some meters are able to calculate your average blood sugar for a period of time, such as over a day or a week. Also, some manufacturers of blood sugar meters make computer programs that use the results from your meter to show patterns in how your blood sugar level changes.

Preventing sore fingers

The more often you test your blood sugar, the more likely you are to have sore fingertips. These suggestions can help prevent sore fingers:

• Do not prick the tip of your finger. If you do, the prick is more painful and you may not get enough blood to get accurate results. Always prick the side of your fingertip. Also, do not prick your toes to get a blood sample. This can increase your risk of developing a dangerous infection in your foot.
• Don't squeeze your fingertip. If you have trouble getting a drop of blood large enough to cover the test area of the strip, hang your hand down below your waist and count to 5. Then, squeeze your finger beginning closest to your hand and moving outward to the end of your finger.
• Use a different finger each time. Establish a pattern for which finger you stick so that you will not use some fingers more than others. If a finger becomes sore, avoid using it to test your blood sugar for a few days.
• Use a different device. Some blood sugar meters use lancet devices that can get a blood sample from sites other than the fingers, such as the forearm.
• Do not reuse the lancet. It can get dull and cause pain.

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Now that you have read this information, you are ready to start monitoring your blood sugar levels at home.

Talk with your doctor

If you have questions about this information, take it to your next doctor visit. You may want to mark areas or make notes in the margins where you have questions.

If you haven't talked with your doctor about when and how often to test your blood sugar, do so during your next visit. Use the blood sugar testing times form to record the times you need to check your blood sugar each day and when you are stressed or ill.

If you would like more information on blood sugar monitoring, the following resources are available:

Computerized records

Many blood sugar meter manufacturers offer computer software programs that compile and analyze blood sugar test results on your home computer. You can print out the results and take them to your next appointment. Some programs will send the information to the doctor electronically. There is also a handheld computer that contains a blood testing device along with tracking programs for diet, blood sugar levels, and medicines.

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