The GDM diagnosis is based on criteria originally proposed by O’Sullivan and Mahan and converted to plasma value by the Nation Diabetes Data Group (NDDG) in 1979.
Diagnosis of GDM requires that at least two of four glucose levels of the100 g OGTT meet or exceed the upper normal limit.
The cut off values for fasting, 1, 2 and 3 hours blood glucose are > 105, 190, 165, and 145 mg/dl respectively