What is a blood glucose test?

In general, a blood glucose test is the measurement of glucose (sugar) levels in your blood at any given time. This test can be used for many things, but it is most commonly used to diagnose or manage diabetes. If you are concerned about an abnormal blood glucose test, talk to your doctor.
A blood glucose test is a laboratory test that measures the level of sugar (glucose) in a sample of your blood. Blood glucose tests may be performed on blood taken after you have fasted for several hours, or randomly during a normal day when you haven't fasted. Your doctor may order a blood glucose test to check to see if you have:
  • hyperglycemia (high blood sugar)
  • hypoglycemia (low blood sugar)
  • diabetes, if you are at risk for the condition
  • prediabetes
  • gestational diabetes (diabetes during pregnancy)
In some people, a blood glucose test can help diagnose diabetes in a very early stage, before symptoms are apparent. Your doctor may also use blood glucose testing as a method for monitoring your sugar levels if you have already been diagnosed with diabetes.

A blood glucose test can also be an important tool for diagnosing other conditions that can affect the level of sugar in your blood. For example, a high glucose level can be caused by an overactive thyroid gland or pancreatic cancer. A low glucose level may be caused by an underactive thyroid gland or a disorder of the pituitary gland.

Continue Learning about Diabetes


Diabetes mellitus (MEL-ih-tus), often referred to as diabetes, is characterized by high blood glucose (sugar) levels that result from the body’s inability to produce enough insulin and/or effectively utilize the insulin. Diabetes ...

is a serious, life-long condition and the sixth leading cause of death in the United States. Diabetes is a disorder of metabolism (the body's way of digesting food and converting it into energy). There are three forms of diabetes. Type 1 diabetes is an autoimmune disease that accounts for five- to 10-percent of all diagnosed cases of diabetes. Type 2 diabetes may account for 90- to 95-percent of all diagnosed cases. The third type of diabetes occurs in pregnancy and is referred to as gestational diabetes. Left untreated, gestational diabetes can cause health issues for pregnant women and their babies. People with diabetes can take preventive steps to control this disease and decrease the risk of further complications.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.