What is the role of oral glucose tolerance test (OGTT) in the workup of glucose intolerance disorders?

Updated: Jul 08, 2020
  • Author: Samuel T Olatunbosun, MD, FACP, FACE; Chief Editor: George T Griffing, MD  more...
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The standard oral glucose tolerance test (OGTT) involves measurement of plasma glucose concentration 2 hours after a 75-g oral glucose load. It is seldom used as a confirmatory test in the diagnosis of diabetes, but it may be helpful in situations where fasting or random glucose results are equivocal. It is required for diagnosing impaired glucose tolerance (IGT), though it is increasingly reserved for research purposes.

A provisional diagnosis of diabetes must be confirmed on a subsequent day by any of three methods: fasting, casual, and OGTT.

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