The ongoing epidemic of obesity and

The ongoing epidemic of obesity anddiabetes has led to more type 2 diabetesin women of childbearing age, with an increasein the number of pregnant womenwith undiagnosed type 2 diabetes (56).Because of the number of pregnantwomenwith undiagnosed type 2 diabetes,it is reasonable to test women with riskfactors for type 2 diabetes (Table 2.3) attheir initial prenatal visit, using standardS20 Classification and Diagnosis of Diabetes Diabetes Care Volume 41, Supplement 1, January 2018diagnostic criteria (Table 2.2). Women diagnosedwith diabetes by standard diagnosticcriteria in the first trimester shouldbe classified as having preexisting pregestationaldiabetes (type 2 diabetes or, veryrarely, type 1 diabetes or monogenic diabetes).GDM is diabetes that is first diagnosedin the second or third trimester ofpregnancy that is not clearly either preexistingtype 1 or type 2 diabetes (see Section13 “Management of Diabetes in Pregnancy”).The International Association ofthe Diabetes and Pregnancy Study Groups(IADPSG) GDM diagnostic criteria for the75-g OGTT as well as the GDM screeningand diagnostic criteria used in the twostepapproach were not derived fromdata in the first half of pregnancy, sothe diagnosis of GDM in early pregnancyby either FPG or OGTT values is not evidencebased (57).