Diabetes: Self Blood Glucose Monitoring (SBGM)

Why is self blood glucose monitoring important?

Measuring blood sugar levels at home has become a cornerstone of diabetes care. Measuring your blood sugar regularly can:

• Help you control your blood sugar to help prevent the complications of diabetes.
• Prevent low blood sugar at night.
• Help you make informed decisions about the amount and type of insulin to use.
• Help you manage illness at home.
• Let you know if you need to do a ketone test.
• Help you understand the effects of certain foods, exercise, and stress on your blood sugar.

Using your blood sugar results to keep your sugar levels normal can help reduce the risk of eye, kidney, heart, blood vessel, and nerve complications.

Self blood glucose monitoring had replaced urine glucose testing for most people. This is because urine testing provides only a rough idea of your blood sugar level. Urine tests cannot tell you what your blood sugar is at the moment you do the test. They also cannot tell you if your blood sugar is too low because sugar does not show in the urine until blood sugar is about 180 mg/dL for most people.

What supplies are needed?

Doing a blood test requires:

• a way to prick the skin to get a drop of blood
• a way to read the results.

Finger-pricking (lancing) device: A finger-pricking device (called a lancet) is used to get the drop of blood. The lancet can often be set at different depths for different people. Adjustable lancets are good for tender skin and for when you do not need the lancet to go deep. Remember to change the lancet every day. A sharp and clean lancet helps prevent injury and infection.

Blood glucose meter (glucometer): Most people use blood glucose meters to test their blood sugar. If meters are not available, color-changing blood sugar strips may be used. Not all meters measure in the same way, so the results from different meters are not always comparable. It doesn't matter which type of meter you choose as long as you consistently use the same meter. Bring your meter to each clinic visit. Your healthcare provider will want to see the information from the meter.

Some features to look for in a meter include:

• accuracy (Make sure the meter is accurate in the environment in which you live, for example, cool or hot temperatures, high humidity, or high altitude.)
• ability to store at least the last 100 test values
• ability to share recorded results at the clinic or at home
• small size for easy carrying
• quick testing time
• ability to check meter accuracy with a control solution or strip.

Test strips: When choosing test strips, make sure they work in the meter you are using. Look for strips that need only a small drop of blood and can draw the blood into the strip. The glucose strips usually cost about $2 to $3 per day, so insurance coverage is important if it is available. Make sure you know what types of strips your insurance will pay for before you choose your meter.

How do I do a blood sugar test?

To get a drop of blood from a finger:

1. Wash the area with warm water. This increases blood flow and makes sure there is nothing on the finger that may change the reading. Do not routinely wipe the finger with alcohol. Any trace of alcohol left on the skin will interfere with the test. Occasionally, when you are away from home (for example, camping or picnics), you may need to use alcohol-free travel wipes to clean the area. If alcohol wipes are the only cleaner available, be sure to let the alcohol dry completely before pricking your finger.
2. Air dry the area before pricking.
3. Use the lancet to prick the side of the finger rather than the fleshy pad on the fingertip (which is more painful). It is often helpful to place the finger on a table. This helps prevent the natural reflex of withdrawing the finger when poked. If the drop is not coming easily, hold the hand down to the side of the body to increase the blood flow to the finger.
4. Put the drop of blood on the strip. (If a test strip has been in a cooler or refrigerator, bring it to room temperature before using.) Make sure you completely cover the required area on the strip with blood. Putting too small a drop on the strip is one of the most common errors.
5. Use your blood glucose meter to measure the sugar level from the strip. If you are using color-changing strips, compare the color to the color chart on the package at the appropriate time. You will have to use a watch with a secondhand and be careful to check the level after the exact amount of time required according to the package directions.

Do I have to prick a finger?

Pricking sites other than the fingers may not hurt as much. The most common alternate site is the forearm. Other places to test include the fleshy part of the hand, upper arm, thigh, and back of the calf. The lancet must be dialed to the maximum depth to get enough blood from these sites. Make sure you have a meter that works for these testing sites.

The main problem with not using the fingertips is that the blood flow through the arm is slower than through the fingers. The slower blood flow means the blood sugar value from the arm is 10 minutes behind the blood sugar value in the fingertip. It is important to rub the site to be used on the arm before pricking. Rubbing increases blood flow in the area. If you are having symptoms of low blood sugar, use the fingertip.

When should I do a blood sugar test?

In general, your healthcare provider will tell you when and how often you need to check your blood sugar. When you have just been diagnosed with diabetes you will need to check your blood sugar more often. After you have your diabetes under control, your provider will tell you how you can decrease your sugar checks.

Some common testing times include first thing in the morning, before meals, before driving, at bedtime, and any time you feel like your blood sugar may be too high or too low. You should check your blood sugar when you are feeling ill.

If you take insulin more than once a day or use an insulin pump, the ADA recommends testing 3 or more times a day.

You may need to test more often when your insulin type or dose has recently changed.

What should the blood sugar level be?

The desired blood sugar levels at different times are:

• fasting or before meals: 90 to 130
• after meals: less than 180 (1 to 2 hours after the time you started a meal)
• bedtime: 100 to 140.

Should I keep written records?

Keeping good records to look for patterns in blood sugars is essential. It is wise to keep written records even if your meter is able to store results (in case the meter breaks). Write down the time of the test, the date, how you feel, and the blood sugar value. You may also want to note times of heavy exercise, illness, or stress. It may be helpful to record what you ate for a bedtime snack or any evening exercise to see if these are related to morning blood sugars. Also, keep a record of when you have low blood sugar reactions and what you think the possible causes were. Always take your blood sugar records to checkups with your healthcare provider.

Good record keeping allows you and the diabetes team to work together most effectively to achieve good diabetes management.