A blood glucose test measures the amount of a type of sugar, called glucose, in your blood. Several different types of blood glucose tests are used.
The A1c is a different type of blood test that can be used to diagnose diabetes or to check your average blood sugar level over the past 2 to 3 months.
Blood glucose tests are done to:
Be sure to tell your doctor about all the non-prescription and prescription medicines and herbs or other natural health products you take. There are many medicines and natural health products that can affect the results of these tests.
Fasting blood sugar (FBS)
For a fasting blood sugar test, do not eat or drink anything other than water for at least 8 hours before the blood sample is taken.
If you have diabetes, check with your doctor to find out how long you need to fast. You may be asked to wait until you have had your blood tested before taking your morning dose of insulin or diabetes medicine.
Random blood sugar (RBS)
No special preparation is needed before having a random blood sugar test.
Oral glucose tolerance test
In the 3 days before this test, eat the way you are used to eating. In general, this means a well-balanced diet that contains at least 150 grams of carbohydrate a day. Good foods to eat are fruits, breads, cereals, grains, rice, crackers, potatoes, beans, and corn.
In the 8 hours right before the test, do not eat or drink anything (except water). Do not smoke, drink alcohol, or exercise.
A health professional takes a sample of your blood.
For a home glucose test, you may have a blood sample taken from your fingertip. This is done by:
For the oral glucose tolerance test:
Watch closely for changes in your health, and be sure to contact your doctor or nurse call line if you have any problems.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.
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Current as of: March 13, 2017
Adam Husney, MD - Family Medicine
& Kathleen Romito, MD - Family Medicine & Matthew I. Kim, MD - Endocrinology & David C.W. Lau, MD, PhD, FRCPC - Endocrinology
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