The lack of a universal protocol for diagnosing GDM has made it impossible to compare different studies of GDM. In addition,
because different investigators have used different protocols for identifying women with the disorder, its true prevalence
is not known. To further complicate matters, there has been ambiguity regarding the maternal and fetal morbidities associated with varying degrees of maternal hyperglycemia. To address these shortcomings, the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study was conducted.