Self-Monitoring of Blood Glucose

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Self-Monitoring of Blood Glucose

Contributor: Dr. Rita Kalyani, MD, MHS 

Self-monitoring of blood glucose (SMBG) refers to the process of home blood glucose testing by persons with diabetes. It is a tool to help persons with diabetes better understand patterns of high and low blood glucose levels during the day. Information from SMBG testing is also used to adjust diabetes medications.

What You Need to Know
Some Key Facts

  1. Blood glucose is monitored at home using a small handheld machine called a glucose meter.
  2. Persons with type 1 diabetes usually need to measure their blood glucose level at least four times a day. Persons with type 2 diabetes who take insulin also need to measure their glucose levels regularly, as recommended by their health care provider. The frequency of glucose monitoring for persons with type 2 diabetes not taking insulin is individualized but usually at least once a day, often in the morning upon awakening and sometimes before other meals and bedtime.
  3. Most glucose meters require a drop of blood from a pinprick of the person’s finger. The blood glucose value is then displayed on the glucose meter’s screen.
  4. The home blood glucose test is useful because the person with diabetes can perform it anywhere and at any time.
  5. The dates, times, and blood glucose readings are all stored in the meter’s memory, which can often hold a few months of readings. These results can be downloaded onto a computer and used by people with diabetes and their providers to make dosing adjustments.
  6. The test strips that come with the meter can give inaccurate readings if they are stored in locations that are too hot or cold or if they expire. It’s important to store the test strips as carefully as you would any medication. Glucose test strips should never be reused, and purchasing pre-owned test strips can result in false results. Each specific glucose meter has its own recommended test strips; if others are used, the glucose meter may fail to provide results or give incorrect glucose readings.
  7. The test strips can give inaccurate readings if a person’s blood glucose level is very high or very low. Persons with diabetes should check with their health care provider if they receive a reading far outside the normal range.
  8. If lotion or food residue is on the skin, blood taken from that area may give an inaccurate reading. First, wash the area or swab it with alcohol to make sure the skin is clean. Hand sanitizers may not always be adequate to clean the skin used for testing.

What Does It All Mean?

  • SMBG is a convenient way for people with diabetes to monitor their blood glucose levels at school, work, or on the road. The test results can help the health care provider and person with diabetes better manage glucose levels.
  • The amount of blood needed for the test is minimal and usually causes no significant discomfort when performed appropriately.
  • The frequency of SMBG differs for each person and depends on the type of diabetes and use of insulin therapy.
  • When used regularly, SMBG can lead to the early identification of potentially dangerous situations, such as diabetic ketoacidosis, severe hypoglycemia (low blood glucose), and facilitate timely and appropriate treatment.


Diabetes Head To ToeDr. Rita Kalyani is an Associate Professor of Medicine at Johns Hopkins University School of Medicine in the Division of Endocrinology, Diabetes & Metabolism. She is an active clinician in the Johns Hopkins Comprehensive Diabetes Center. Dr. Kalyani directs the Diabetes Management Service for Johns Hopkins’ Total Pancreatectomy Islet Auto Transplant Program. She is a new member of the DiabetesSisters Board of Directors.

This excerpt is taken from the recently published book “Diabetes Head to Toe: Everything You Need to Know about Diagnosis, Treatment, and Living with Diabetes” by Dr. Rita Kalyani, Dr. Mark Corriere, Dr. Thomas Donner, and Dr. Michael Quartuccio. Published by Johns Hopkins University Press © 2018. Reprinted by permission of the publisher.