There remains some disagreement on the use of the oral glucose tolerance test (OGTT) in diabetes testing and diagnosis. Those that recommend using OGTT assert that the OGTT better detects diabetics who are at risk for developing complications associated with diabetes.
One of the ADA's 2015 criteria options for diagnosis of diabetes is the use of a 2-hr plasma glucose (PG) ≥200 mg/dL during OGTT (75 g). The OGTT is performed as described by the WHO, using glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water.
The OGTT is typically utilized to diagnose gestational diabetes. Those at risk for gestational diabetes are screened with FPG, casual, and sometimes a 50 g oral glucose load. Definitive diagnosis of gestational diabetes is made with an OGTT, providing a glucose challenge of 100 g or 75 g glucose and timed blood glucose measurements.