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Criteria for Diagnosing Diabetes

Topic Overview

To be diagnosed with diabetes, you must meet one of the following criteria:1

  • Have symptoms of diabetes (increased thirst, increased urination, and unexplained weight loss) and a blood sugar level equal to or greater than 200 milligrams per deciliter (mg/dL). The blood sugar test is done at any time, without regard for when you last ate (random plasma glucose test or random blood sugar test).
  • Have a fasting blood sugar level that is equal to or greater than 126 mg/dL. A fasting blood sugar test (fasting plasma glucose) is done after not eating or drinking anything but water for 8 hours.
  • Have a 2-hour oral glucose tolerance test (OGTT) result that is equal to or greater than 200 mg/dL. An OGTT is most commonly done to check for diabetes that occurs with pregnancy (gestational diabetes).
  • Have a hemoglobin A1c that is 6.5% or higher.

The diagnosis of diabetes needs to be confirmed by repeating the same blood sugar test or doing a different test on another day.

If the results of your fasting blood sugar test are between 100 mg/dL and 125 mg/dL, your OGTT result is between 140 to 199 mg/dL (2 hours after the beginning of the test), or your hemoglobin A1c is 5.7% to 6.4%, you have prediabetes. This means that your blood sugar is above normal but not high enough to be diabetes. Discuss with your doctor how often you need to be tested.1

References

Citations

  1. American Diabetes Association (2012). Diagnosis and classification of diabetes mellitus. Diabetes Care, 35(Suppl 1): S64–S71.

Credits

By Healthwise Staff
E. Gregory Thompson, MD - Internal Medicine
David C.W. Lau, MD, PhD, FRCPC - Endocrinology
Last Revised July 16, 2013

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