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How to Test Your Blood Sugar

Written by: Melissa Herrmann Dierks , RDN, LDN, CDCES
How to Test Your Blood Sugar

Blood sugar testing is easier than ever for people who have been diagnosed with diabetes or prediabetes. Today’s blood glucose meters are fast, accurate, easy, and only require a very small drop of blood. Finding out what your blood sugar is in 5 seconds or less is a valuable tool to help prevent complications from diabetes by helping you learn how food, activity, and other factors can affect your blood sugar levels.

Checking blood sugar before and after meals teaches you how to adjust your diet, and also helps your healthcare provider know how to best adjust medications and/or insulin to your needs. In this article, we explain how to check your blood sugar as well as a few additional considerations.

Who should test their blood sugar?

Home blood glucose testing is typically recommended for:

  • People who take insulin to control blood sugar levels, whether through an insulin pump or daily injection
  • Pregnant women with gestational diabetes
  • Those with a high A1C level
  • People who are on oral or injectable diabetes medications and having high or low blood sugar
  • People who want feedback on how to adjust their diet to help improve blood sugar

There is some controversy about the cost-benefit of having people with type 2 diabetes on oral medications check their blood sugar at home. However, many certified diabetes educators feel that it can be helpful to spot trends of highs or lows, and to learn about how different foods affect you. This can help keep blood glucose levels in a healthy range.

What blood glucose meter should I use?

A variety of blood glucose meters are available on the market. Most are generally fast and portable, allowing you to conveniently test at home or on the go.

Think about what features are important to you in a meter. Are you interested in 30/60/90-day averages? Do you want to test on an alternate site other than your finger? Is a backlight important for testing in the dark? Do you want Bluetooth connectivity?

Choosing a glucose meter can come down to many factors, so use these tips to find one that best fits your lifestyle. Since the readings from your glucose meter will be used for making decisions about your health, make sure you pick one that is accurate and reliable.

How do I check my blood sugar level?

A blood glucose meter usually comes in a kit. All kits provide a meter and user guide, but only some kits include everything you need to test (a meter, lancing device to prick your finger, lancets, and test strips).

Control solution is an optional item you may want to practice testing your blood sugar without having to prick your finger, or to confirm that the meter and test strips are working as expected.

Make sure you have all the necessary supplies you need to get started:

  • Blood glucose meter
  • Lancing device and lancet (for getting a drop of blood)
  • Test strip
  • Batteries for the blood glucose meter (typically included)

Some meters allow for alternate site testing — such as using areas of the forearm or leg — so those kits may come with an alternate site testing cap for the lancing device. Although most blood glucose meters use similar steps, refer to the user manual included with your kit for details on using your specific model.

 

In general, the following steps cover how to test your blood sugar:

    1. Wash your hands using soap and warm water, rinse, and thoroughly dry to make sure your fingers are clean. Don’t use alcohol on your hands because it may affect your test result.
    2. Prepare the lancing device by inserting a lancet, twisting off the cover of the lancet, and replacing the lancing device cap. Cock the handle on the lancing device so that it is in the ready position.
    3. Insert the test strip into the meter. Most meters turn on automatically when a test strip is inserted. Note: The first time that you use your meter, it may ask you to enter the correct date and time for your time zone, or to confirm other information before you can begin a test.
    4. Choose a spot on your finger (or an alternate site if applicable for your meter) where you want to test. Try an area on the finger that is most comfortable for you, such as the side of your fingertip and not close to the fingernail. Hold the lancing device firmly against the skin and press the button to lance the site and get a drop of blood. Alternate between using a different finger or site each time you test.
    5. Touch and hold the sample area of the test strip to the drop of blood until the test strip has absorbed enough blood to begin the test.
    6. View the test result on the meter and record it on a blood glucose log sheet.
    7. Discard the used lancet and test strip properly, following the instructions of your healthcare provider.

The user’s manual included with your glucose meter will review how to set up the meter, use the lancing device (if included), test strips, and any other items in the kit. Please refer to this information for more details on how to perform a blood glucose test.

If you check your blood glucose and the number on the glucose meter does not match your symptoms, thoroughly wash and dry your hands and repeat the test.

When should I check my blood sugar level?

Discuss your testing schedule with your healthcare provider or certified diabetes educator. Keeping an accurate blood glucose log will help your healthcare provider spot patterns in your blood glucose, which helps to determine if insulin or medications should be adjusted, or if any other therapy adjustments will help you better reach your target blood glucose range.

Consider testing at different times of the day to get more information about your blood sugar levels, including:

  • First thing in the early morning before eating. This will give you a fasting blood sugar level.
  • Before meals and 2 hours after the first bite of a meal to learn how the meal affected your blood sugar. This is can be especially helpful when eating at a restaurant and when trying new foods or diets. Incorporate regular tests 2 hours after meals throughout the week, unless otherwise advised by your healthcare provider.
  • In the middle of the night, if instructed by your healthcare provider.
  • Before driving if you take blood glucose lowering medications or if your blood sugar is unstable.
  • Before exercise and more frequently for the next 24 hours after exercise.
  • If you are sick, have urine ketones, or are under stress.

What should my blood sugar numbers be?

Blood glucose targets are individualized based on age, health, insulin or medication dose, level of activity and other factors. The American Diabetes Association provides a general recommendation for those with diabetes to keep blood glucose between 80-130 mg/dL before meals and less than 180 mg/dL 2 hours after the start of a meal.

It’s important to understand that blood glucose levels of 70 mg/dL or below require immediate attention to treat hypoglycemia, which is when your blood sugar has dropped too low. Any time you see a low value on your blood glucose meter, follow the 15-15 rule, which is to take 15 grams of a fast-acting carbohydrate (glucose tablets, juice, candies) and re-check your blood sugar after 15 minutes.

High blood sugar can also cause short term and long-term physical effects. If you have two or more unexpected consecutive readings above 250 mg/dL, let your healthcare provider know.

Additional considerations

You may want to keep a blood glucose meter and test strips at work or school for testing when away from home. Some people will also keep a meter and test strips in the car, but care needs to be taken to protect the items from excessive heat as this can affect their performance. Store your meter and test strips according to the temperature range listed on the container or the owner’s manual for your device.

It’s also helpful to have plenty of test strips and lancets on hand, and to take extra supplies with you when traveling. Always check the expiration date on test strips and the use life of the test strips once the vial is opened. The manufacturer will let you know how many days this is — for instance, 180 days once the vial is opened, so refer to their instructions for more details. It’s also best to change lancets with each test to keep testing comfortable.

Make sure to keep an up-to-date blood sugar log of your numbers and take your log to all healthcare provider and diabetes education appointments. Don’t panic if a blood sugar number is above or below target, and notify your healthcare provider when appropriate. It may be tempting to think of a number on your glucose meter as good or bad, but don’t judge yourself. This number is just letting you know information about your current state and helps your healthcare provider to know if any adjustments need to be made to your diabetes care plan.

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Written by: Melissa Herrmann Dierks , RDN, LDN, CDCES

Melissa Herrmann Dierks RDN, LDN, CDCES is a Registered Dietitian Nutritionist, Certified Diabetes Care and Education Specialist, and Licensed Dietitian Nutritionist in Huntersville, NC with over twenty-five years of professional experience in the field of nutrition and diabetes education. In addition to providing nutrition solutions for adults and children, she provides nutrition communication services to the food and beverage industry and is the owner of Supermarket Savvy. Melissa has held various sales and marketing positions for leading companies in the diabetes space including insulin pump, blood glucose monitor, and diabetes supply distribution companies.

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