Measuring blood sugar (glucose) levels at home has become a cornerstone of diabetes care. Measuring your blood sugar regularly can:
For most people blood sugar testing has replaced testing their urine for sugar. This is because urine testing gives only a rough idea of the blood sugar level. Urine tests do not 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. Sugar usually does not show in the urine until blood sugar is at least 180 milligrams per deciliter (mg/dL).
Doing a blood test requires:
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 the same. It doesn't matter which type of meter you choose as long as you always 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:
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.
Different meters have different instructions so it is important to learn how to test using your meter. It is best to have your provider, diabetes educator, or pharmacist show you how to use your meter. Then, test your blood sugar in front of them so they can check that you are doing it correctly. It is also a good idea to have family members learn how to test your blood
To get a drop of blood from a finger:
Avoid inaccurate (wrong) blood sugar results by making sure:
You can prick other parts of your body instead of a finger. Pricking other sites 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 blade or needle 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. If you are going to prick another site, such as your arm, rub the site before pricking. Rubbing increases blood flow in the area. If you are having symptoms of low blood sugar, prick your fingertip. It’s faster and you will know what your blood sugar level is more quickly.
There are ways to stick your finger that are less painful. For example, you can try:
Also, washing your hands in warm water (and then drying them well) makes it easier to get a good drop of blood.
A continuous glucose monitor may be useful if you take frequent insulin doses to keep your blood sugar in a very narrow range. These devices sense blood sugar under the skin and display the reading on a screen. They can also be set to sound an alarm when blood sugar reaches a certain low or high point.
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 American Diabetes Association (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.
The desired blood sugar levels at different times are:
The American Diabetic Association recommends a blood sugar of 70 to 130 when you are fasting or before meals. However, some people start having symptoms of low blood sugar at a blood sugar below 90 mg/dL (5 mmol/L). Ask your provider what upper and lower blood sugar goals he or she recommends for you. Also ask your provider to write down what you should do if your blood sugar result is too high or too low.
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 when you exercised, were sick, or felt stressed. 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. You can then share this diary with your provider or diabetes educator and they can help you learn what changes your blood sugar, and this will help you control it better.