The WHO uses the 75 gr.oral
glucose load, and the diagnosis is based on the fasting and 2-hr blood glucose
levels. In contrast, the NDDG and the Coustan modification, uses a 100 gr.
glucose load and the diagnosis is based on four measurements (fasting, 1, 2 and
3 hr. glucose levels). It is also important to note, that the diagnostic blood
glucose levels are lower by the NDDG than by the WHO method, and even lower by
Coustanís method. Differences in the diagnostic methods and criteria used in
different geographic areas could account, at least in part, for reported
differences in the prevalence of GDM.