Glucose challenge test does not predict gestational diabetes mellitus

Objective It is widely acknowledged that identification and treatment of gestational diabetes mellitus (GDM) results in better maternal and neonatal outcomes. However, the utility of the glucose challenge test (GCT) remains controversial regarding the diagnostic approach and decision making. Methods We performed a retrospective analysis on the database of our Laboratory Information System to retrieve results of GCT and oral glucose tolerance test (OGTT), which were performed on consecutive female outpatients referred by the gynecologists over the last 3 years. Results Cumulative results for GCT and OGTT were retrieved for 724 female outpatients and screening test was abnormal in 114 of them. This group was classified in terms of normal glucose tolerance (NGT), one abnormal value for the 100-g-3h OGTT (OAV) and GDM. GDM was diagnosed only in 34 subjects (4.7%). No statistically significant differences were observed in the basal plasma glucose and 1-h GCT values among groups. Multivariable logistic regression analysis demonstrated that age, OGTT values >= 180 mg/dL at 1 hour and OGTT values >= 155 mg/dL at 2 hours, but not GCT values, were independent predictors for GDM (p = 0.048, p = 0.012 and p < 0.001, respectively). Conclusions Results of our retrospective analysis on an unselected population are consistent with the hypothesis that GCT is not predictive of GDM and its diagnostic significance remains questionable.