oral glucose tolerance test
(redirected from OGTT)Also found in: Acronyms.
oral glucose tolerance test
,OGTT
A screening test for diabetes mellitus (DM), in which plasma glucose levels are measured after the patient consumes an oral glucose load. In screening patients for type 2 DM, measuring fasting plasma glucose levels or checking a hemoglobin A1c level is generally preferable to an OGTT because the former tests are simpler, cheaper, and better tolerated by patients. An OGTT reveals type 2 DM when plasma glucose levels exceed 200 mg/dl 2 hr after drinking a 75-g glucose load. Plasma glucose levels between 140 mg/dl and 199 mg/dl suggest impaired glucose tolerance.
Gestational Diabetes Mellitus
In pregnancy, a modified OGTT is used to screen women with risk factors for gestational diabetes (GDM), including obesity, family history of type 2 DM, age greater than 25 years, and a history of unexplained stillbirths. At 24 to 28 weeks' gestation, a 50-g glucose load is given; 1-hr plasma glucose levels greater than 140 mg/dl constitute a positive screening result. Any patient having a positive test result should then undergo a 2-hr, 100-g OGTT to determine whether GDM is present. See: table
Time: | Glucose level exceeds: |
---|---|
Fasting | 92 mg/dl |
60 min | 180 mg/dl |
120 min | 155 mg/dl |
180 min | 140 mg/dl |
Medical Dictionary, © 2009 Farlex and Partners