RESUMO
Even though the 50 g oral glucose challenge test [GCT] is the most commonly used screening modality for gestational diabetes mellitus [GDM], no consensus for the diagnostic approach is available to patients with a markedly elevated GCT result. We aimed to evaluate the diagnostic utility of markedly elevated GCT results and the impact of age using the oral glucose tolerance test [OGTT] as gold standard. Retrospective study conducted in a women's hospital in Ankara, among patients who underwent GCT from January 2005 to December 2008. In this retrospective study, we included 626 pregnant women who underwent a 3-hour 100 g OGTT after a GCT result >/= 180 mg/dL among 29 842 women. We calculated positive predictive values [PPV] of each GCT category to diagnose GDM and both GDM and gestational impaired glucose tolerance [GIGT]. A GCT result of >/= 240 mg/dL provided 100% PPV for the diagnosis of GDM and a result of >230 mg/ dL provided 100% PPV for the diagnosis of GDM + gestational impaired glucose tolerance [GIGT], according to both, National Diabetes Data Group [NDDG] and Carpenter and Coustan [CC] criteria. A result of >/= 200 mg/dL provided 100% PPV for diagnosing GDM+GIGT in patients older than 35 years, according to the CC criteria. The GCT result of 200 mg/dL is an ideal cutoff value for the diagnosis of GDM + GIGT in patients >/= 35years, and OGTT can be omitted in these patients. In younger patients, the cutoff value should be chosen as 230 mg/dL