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

BACKGROUND: 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 first trimester and conducting preventive interventions is of great importance. This study aimed to define the predictive value of fasting plasma glucose (FPG) and fasting plasma insulin (FPI) test in first trimester concerning the positive result of oral glucose challenge test (OGCT). MATERIALS AND METHODS: This is a prospective and observational study conducted on 88 pregnant women in Tehran. After FPG and FPI measurements in these women in the first 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 significant. RESULTS: 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 specificity of 45.2-47%. CONCLUSIONS: Only higher fasting glucose levels in early pregnancy, within the normoglycemic range, would predict the development of glucose intolerance with limited sensitivity and specificity.