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A blood sugar test is a simple procedure that measures the amount of sugar, or glucose, in the blood. It is performed by obtaining a small sample of blood and analyzing it. Blood can be obtained from a vein puncture or through a finger stick.
Glucose is one of the body’s main sources of energy. Food containing carbohydrates, such as grains and fruits, is converted into glucose and raises blood sugar levels in the body. A blood sugar test measures the amount of glucose in the blood. It can be useful in diagnosing diabetes. It can also help people with diabetes manage their condition.
Testing glucose levels helps identify when your blood sugar is too high or too low. Most people with diabetes can benefit from testing their blood sugar levels. However, different times may be recommended for different people.
For people who are taking insulin, testing glucose levels before meals can help them decide how much insulin to take. For people on medications that increase insulin levels in the body, testing glucose levels can help them decide the right dose to take or how much carbohydrate to eat.
Pregnant women benefit from frequent testing, which can help them be sure that their blood glucose values are in a healthy range. Even people who have diabetes but who are not on medication that increases insulin can use blood glucose tests to see how much their blood sugar changes after meals or exercise.
Blood sugar tests do not usually cause many side effects. Blood sugar tests performed through a vein puncture can cause swelling and bruising at the puncture site. Blood sugar tests performed with a finger stick do not usually cause side effects other than possible soreness at the puncture site.
A blood sugar test can be performed in the hospital, but these tests are also routinely done at home. If a blood sample is taken from the vein, the procedure will usually be done at the hospital or in a lab by a trained technician or phlebotomist. Most often, blood sugar levels are tested using a blood glucose meter. This device requires that a small drop of blood be put on a strip. This strip is inserted into the meter, and the meter reports the amount of sugar found in the blood.
The exact steps vary depending on the type of glucose meter a person is using. The steps for blood sugar testing usually include:
Regular blood sugar testing can play a critical part in managing diabetes. Monitoring blood sugar levels also provides information on how well a person’s diabetes is being controlled and how stable blood sugar levels are. Testing can help a person with diabetes decide whether his or her treatment plan needs to be adjusted.
For example, if your blood sugar levels are always too high after eating breakfast, you and your healthcare team could take steps to help lower them, such as eating breakfasts that are lower in carbohydrates, taking morning walks, or increasing medication.
Very few risks are associated with a blood sugar test. Any time the skin is punctured, infection is a risk, but this is very unlikely. Not having enough blood or getting an inaccurate reading are also risks of the procedure.
Some blood sugar tests require preparation. Fasting blood sugar tests require that a patient refrain from eating for between 8 and 12 hours before the test. Non-fasting blood sugar tests do not require any special preparation.
Written by: MaryAnn DePietro
Medically reviewed : Peggy Pletcher, MS, RD, LD, CDE
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