How to Self-Monitor Blood Glucose

For a loved one with diabetes, monitoring blood glucose levels is crucial.

“Self-monitoring of blood glucose (SMBG testing) provides a map that guides decisions and changes in treatment components to improve diabetes control,” says Susan McLaughlin, American Diabetes Association president-elect, Health Care and Education. “Tracking patterns helps individuals know when they’re at greatest risk of very high or very low blood glucose, which can increase the risk of falls, result in fracture, decrease mobility, diminish quality of life, and lead to depression.”

Today’s blood glucose monitors are portable, accurate, and reliable. Test results are sometimes reported in as little as five seconds, and almost always in less than a minute. Some are easier to use than others, require less blood for testing, and store more data. Error codes, automatic timers, and barcodes make calibrating the units less complicated, and large display screens allow people with limited vision to read test results. Some monitors provide audible testing instructions and announce test results. Some speak Spanish.

Some monitors measure glucose in blood from parts of the body other than a fingertip. Many patients find this alternate site testing less painful than fingersticks, and results are similar when blood glucose isn’t changing rapidly. Values vary after a meal or during hypoglycemic episodes. That’s because blood taken from a fingertip measures “real-time” glucose levels. It’s the most accurate indicator of how successfully low blood sugar has stabilized after treatment.

How To Test Blood Glucose Levels

To perform SMBG testing:

• Place a small amount of blood on a disposable test strip coated with chemicals that combine with glucose. 
• Insert the strip into the monitor, which measures glucose by determining how much electricity can pass though the blood sample or how much light reflects from it.
• The glucose level appears as a number on the monitor. Some monitors store test results, which can be transferred to a computer and printed or sent to the doctor.

Even if the monitor has a memory, it’s important to keep a written record of results. These notes, which should include information about diet, activity, and the time the tests were taken, show how and when blood glucose values change. Take the record book to every appointment with the doctor or diabetes educator.

Inserted under the skin, continuous glucose monitors measure glucose levels in fluid around cells. Sensors relay information to a beeper-sized box or to a compatible insulin pump, which stores it. “The sensors track blood sugar trends,” McLaughlin notes. “One shows how rapidly and for how long after a meal blood sugar rises or falls. This indicates whether insulin, food intake, or exercise should be adjusted.”

Someone who has memory problems or difficulty understanding instructions or who cannot prepare and insert a test strip won’t be able to do SMBG testing. A caregiver must learn to perform these tasks.

The diabetes educator will teach you or your loved one to:

• Prepare the puncture site 
• Make sure circulation is adequate at the site
• Use several different blood glucose monitors 
• Handle and store monitors properly
• Retest if results don’t reflect how he or she feels 
• Contact the doctor if the problem continues
• Dispose of used test strips, lancets, and other waste materials
• Change batteries when Daylight Saving Time goes into effect