Prediction of glucose intolerance at 24-28 weeks of gestation by glucose and insulin level measurements in the first trimester

Gestational diabetes is the second common disorder in pregnancy period, which is detected in 24-28 weeks of gestational age through screening tests in low-risk women. The women with gestational diabetes are prone to prenatal mortality and development of future diabetes. Therefore, detection of these individuals in the fi rst trimester and conducting preventive interventions is of great importance. This study aimed to defi ne the predictive value of fasting plasma glucose (FPG) and fasting plasma insulin (FPI) test in fi rst trimester concerning the positive result of oral glucose challenge test(OGCT). This is a prospective and observational study conducted on 88 pregnant women in Tehran. After FPG and FPI measurements in these women in the fi rst trimester, a screening test of GCT with 50 g oral glucose was conducted in 24-28 weeks of gestational age. Diagnostic value of FPG and in these two groups of positive and normal GCT results was evaluated through receiver operator characteristic (ROC) curve. P < 0.05 was considered signifi cant. In this study, 15 subjects (17%) were detected with a positive GCT result. The sub-curve area of ROC diagram for FPG and FPI was calculated to be 0.573and 0.592, respectively, which reveals that FPG and FPI cannot have a proper predictive value for the positive result of GCT. Based on the results, the best cutoff points for FPG and FPI are 79.5 mg/dl and 7.55 μIU/ml, with accuracy of 60-67% and specifi city of 45.2-47%. Only higher fasting glucose levels in early pregnancy, within the normoglycemic range, would predict the development of glucose intolerance with limited sensitivity and specifi city.