Criteria for Diagnosing Diabetes

Topic Overview

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

  • Have symptoms of diabetes (increased thirst, increased urination, and unexplained weight loss) and a blood sugar level equal to or greater than 11.1 millimoles per litre (mmol/L). 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 7.0 mmol/L. 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 11.1 mmol/L. 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. (This test is most reliable for adults. Some experts recommend using one of the other tests to diagnose diabetes in children.)footnote 2 This test may not be appropriate for everyone because many things can affect the lifespan 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.

Your doctor may repeat the test to confirm the diagnosis of diabetes.

If the results of your fasting blood sugar test are between 6.1 to 6.9 mmol/L, your OGTT result is between 7.8 to 11.0 mmol/L (2 hours after the beginning of the test), or your hemoglobin A1c is 6.0% 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.footnote 1

References

Citations

  1. Diabetes Canada Clinical Practice Guidelines Expert Committee, et al. (2018). Definition, classification and diagnosis of diabetes, prediabetes and metabolic syndrome. Canadian Journal of Diabetes, 42(Suppl 1): S10–S15. DOI: 10.1016/j.jcjd.2017.10.003. Accessed October 15, 2018.
  2. Diabetes Canada Clinical Practice Guidelines Expert Committee, et al. (2018). Type 2 diabetes in children and adolescents. Canadian Journal of Diabetes, 42(Suppl 1): S247–S254. DOI: 10.1016/j.jcjd.2017.10.037. Accessed October 15, 2018.

Credits

Current as ofJuly 25, 2018

Author: Healthwise Staff
Medical Review: E. Gregory Thompson MD - Internal Medicine
Anne C. Poinier MD - Internal Medicine
Kathleen Romito MD - Family Medicine
Adam Husney MD - Family Medicine
David C.W. Lau MD, PhD, FRCPC - Endocrinology
Matthew I. Kim MD - Endocrinology

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