Values are expressed in mg/dL (mmol/L). a100 g OGTT; b75 g OGTT. Gestational pre-diabetes is confirmed when there is an abnormal result in the GCT test and either normal or 1 abnormal OGTT test result [23,24]. If there are two or more abnormal values in the OGTT, the patient is diagnosed with GDM . C&C, Carpenter and Coustan; GCT, glucose challenge test; NDDG, National Diabetes Data Group; OGTT, oral glucose tolerance test; WHO, World Health Organization.