Your Test: Diabetes Testing

You may need a test for diabetes if you have been having symptoms of abnormal blood sugar. Or you may need it if you have a higher risk of getting diabetes.

Symptoms of abnormal blood sugar include feeling more hungry or thirsty than usual. You may have to urinate more, especially at night. You may have lost weight, feel very tired, and have blurry vision.

Testing, or screening as it is sometimes called, is easy. All it takes is a simple blood test that can be done at your doctor's office or a lab.

Should you be tested for diabetes?

Talk with your doctor about what is putting you at risk for diabetes and whether you should be tested. Some experts recommend testing for type 2 diabetes in people who are overweight or obese and are ages 35 to 70. Other experts suggest screening for diabetes at any age if you have a history of gestational diabetes or are overweight and have other risk factors. They also recommend screening at age 35 even if you don't have symptoms or risk factors. You are considered overweight if your body mass index (BMI) is 25 or above. (In Asian Americans, screening is recommended if your BMI is 23 or above). Your BMI is a measure of your weight compared with your height. For example, a person who is 6 feet tall and weighs between 185 to 225 pounds is considered overweight. Your doctor can help you find your BMI.

If you are overweight, you should consider a test if:

  • You have a parent or sibling who has type 2 diabetes.
  • You are African American, Hispanic, Native American, Asian American, or Pacific Islander.
  • You have prediabetes. This means your blood sugar is above normal but is not high enough to be diabetes.
  • You have a history of heart disease.
  • You have high blood pressure.
  • Your high-density lipoprotein (HDL) cholesterol is low and/or your triglyceride level is high.
  • You had gestational diabetes.
  • You do not get any exercise.
  • You have polycystic ovarian syndrome (PCOS).

How is the test done?

There are several different tests. Your doctor will decide which one you need.

  • 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.
  • A1c test estimates your average blood sugar level over the last 2 to 3 months. It can be done any time during the day, even after a meal. Recent changes in diet, exercise, or medicines do not affect the test results. This test may not be appropriate for everyone because many things can affect the life span of red blood cells, such as the second or third trimester of pregnancy, a recent blood loss or a blood transfusion, sickle cell disease, hemodialysis, or erythropoietin (ESA) medicine.
  • Random blood sugar (RBS) measures blood glucose no matter when you last ate. Several tests may be taken throughout the day. Random testing is useful because glucose levels in healthy people do not change much during the day. Blood glucose levels that vary widely may indicate a problem.
  • Oral glucose tolerance test (OGTT) is used to diagnose diabetes that occurs during pregnancy. This test is a series of blood tests done after you drink a sweet liquid that contains glucose. This test is sometimes used for diagnosing diabetes in someone who is not pregnant.

How often do you need the test?

Talk to your doctor about how often to be tested. Some guidelines suggest:

  • If you are 35 or older, you should have the test every 3 years.
  • If you have any of the health issues listed above, such as prediabetes, you should have a test more often.

Do you have any questions or concerns after reading this information? It's a good idea to write them down and take them to your next doctor visit.