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How do health care providers diagnose diabetes?

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The most common test for diagnosing any kind of diabetes is a one-step approach called the oral glucose tolerance test. Prior to the test, you can’t eat or drink anything (except water) for between 4 and 8 hours. A health provider tests your initial sugar level and then gives you a sugar drink. Then your sugar level is checked every 30 to 60 minutes for up to 3 hours.1,2

Although the NICHD studies different aspects of all types of diabetes, the NICHD is not the primary resource for patient information about type 1 or type 2 diabetes. The National Diabetes Information Clearinghouse and the National Diabetes Education Program provide detailed information about type 1 and type 2 diabetes, including specific information about diagnosis and glucose levels.

Risk for type 1 diabetes

Health care providers can use a test to check for certain blood markers that can predict how likely it is that someone will develop type 1 diabetes. These blood markers signal that the immune system is attacking the beta cells of the pancreas. Having two or more of these markers, called antibodies, is associated with higher risk of developing type 1 diabetes over the next 10 years.3

Testing for gestational diabetes

Health care providers will consider a woman’s risk factors and current health before testing for gestational diabetes. If a woman is at high risk for gestational diabetes, her health care provider will test her as soon as she knows she is pregnant. If a woman is at low risk for gestational diabetes, her health care provider might not test her at all, or will test her between 24 weeks and 28 weeks of pregnancy. For more information about testing for gestational diabetes, see the NICHD’s Am I at risk for gestational diabetes? brochure.


  1. National Institute of Diabetes and Digestive and Kidney Diseases Diabetes website. (2011, December). Am I at risk for type 2 diabetes? Taking steps to lower your risk of getting diabetes. Retrieved May 22, 2012, from http://diabetes.niddk.nih.gov/dm/pubs/riskfortype2/#1 [top]
  2. National Library of Medicine (2011, May). Glucose tolerance test. Retrieved May 22, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/003466.htm [top]
  3. National Institute of Diabetes and Digestive and Kidney Diseases DPT Trial website. (n.d.). Type 1 diabetes prevention trials questions & answers. Retrieved May 21, 2012, from http://archives.niddk.nih.gov/patient/dpt_1/diabetes_qa.aspx [top]

Last Updated Date: 10/23/2013
Last Reviewed Date: 09/17/2013
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