Can either oral glucose challenge test or oral glucose tolerance test parameters predict gestational diabetes mellitus?

This study aims to evaluate the relationship between the glucose challenge test (GCT) levels and any of the oral glucose tolerance test (OGTT) parameters (fasting plasma glucose (FPG), 1-, 2-, or 3-h plasma glucose levels) and their effect on predicting gestational diabetes mellitus (GDM). This analysis was carried out as a retrospective study at Obstetrics and Gynecology Clinic of Turgut Özal University Hospital. Oral GCT were conducted on patients who are at 24–29 weeks’ gestation. The study participants with positive GCT results underwent a 3-h, 100-g OGTT, and the resulting values were evaluated using Carpenter and Coustan diagnostic criteria to determine the gestational glucose tolerance status of patients. The data obtained from both tests (GCT, FPG, 1-, 2-, 3-h OGTT values) were analyzed to observe the effect of each group on predicting GDM. Although all of the GCT and OGTT values were found to be statistically significant (p < 0.001) in determining GDM, the 2-h values of OGTT detected almost all GDM cases with a very high sensitivity level (94.5 %). The 1-h values on the other hand identified 87.6 % of GDM (p < 0.001). The GCT value with the highest sensitivity and specificity for predicting GDM was calculated as 154.50 mg/dl (sensitivity and specificity rates were 79.2 and 72.8 %, respectively). A 2-h OGTT glucose level can detect GDM with 94.5 % sensitivity. This result can guide clinicians to evaluate the patients with GDM.