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What is a blood sugar test?
A blood glucose (blood sugar) test measures the amount of a type of sugar, called glucose, in your blood.

Several different types of blood glucose tests are used.
  • Fasting blood sugar (FBS) measures blood glucose after you have not eaten for at least 8 hours. It often is the first test done to check for diabetes.
  • 2-hour postprandial blood sugar (2-hour PC) measures blood glucose exactly 2 hours after you eat a meal.
  • Random blood sugar (RBS) measures blood glucose regardless of when you last ate. Several random measurements may be taken throughout the day. Random testing is useful because glucose levels in healthy people do not vary widely throughout the day. Blood glucose levels that vary widely may indicate a problem. This test is also called a casual blood glucose test.
  • Oral glucose tolerance test is used to diagnose diabetes that occurs during pregnancy (gestational diabetes). An oral glucose tolerance test is a series of blood glucose measurements taken after you drink a sweet liquid that contains glucose.