RESUMEN
AIMS: This study aimed to investigate the relationship between fasting plasma glucose in the first trimester of pregnancy and the incidence of gestational diabetes. METHODS: This descriptive-analytical study was conducted using the merging data from two prospective cohort studies that were carried out from 2015 to 2018 in Ahvaz, southwest of Iran. Logistic regression and ROC curves were used to evaluate the predictive power of risk factors. RESULTS: Of all 1270 pregnant women studied, 454 (35.75%) had gestational diabetes who were compared with the other 816 (64.25%) healthy women. The area under the curve (AUC) of fasting glucose for the first pregnancy visit was 0.80 (95% CI: 0.76-83), and the optimum fasting glucose cut-off point was 85.5 mg/dL with a sensitivity of 71% and a specificity of 69%. AUC of the combination of fasting glucose at the first visit with body mass index ≥25 kg/m2 and family history of diabetes was calculated to be 0.85 (CI, 0.82-0.88) and 0.84 (CI, 0.79-0.89) respectively. CONCLUSION: Fasting plasma glucose in the first trimester of pregnancy is a relatively good predictor of gestational diabetes. If this factor is combined with other risks, its diagnostic value will increase.