Endocrine Abstracts

Introduction: Screening for gestational diabetes (GD) in the first trimester using fasting plasma glucose (FPG) ≥92 mg/dl is routinely performed in several countries. However, evidence on the benefits and harms of early universal screening, as well as the optimal cut-off of FPG, is conflicting. This results in lack of standardised screening and treatment approaches for GD worldwide.

Aims: o compare the use of pharmacological treatment and pregnancy outcomes in GD diagnosed in the first and second trimesters, as well as between different levels of FPG in the first trimester.

Materials and methods: Retrospective cohort study of singleton pregnancies with GD that were followed in a tertiary centre (2016-2020). Cases of first-trimester-diagnosed GD were divided in 3 groups according to their FPG level (G1: 92-94 mg/dl, G2: 95-100 mg/dl, G3: >100 mg/dl). All women received guidance on lifestyle behavior changes. Neonatal morbidity included respiratory distress syndrome, hypoglycaemia and/or hyperbilirubinaemia.

Results: 1498 pregnancies were analysed, with mean maternal age of 34.0±5.4 years and pregestational BMI of 27.1±5.9 kg/m² 48.8% diagnosed in the first trimester. Compared to second-trimester, first-trimester GD showed a greater need for pharmacological treatment (43.0% vs 26.4%, P<0,001) and earlier start of insulin treatment (19.7±7.1 vs 30.9±3.1 weeks, P<0.001); with no differences in pregnancy outcomes. FPG in the first-trimester-diagnosed GD was 92-94 mg/dl in 46.0%, 95-100 mg/dl in 36.8% and > 100 mg/dl in 17.2%. Pregestational BMI was superior in G3 (28.5±6.8 vs 26.8±6.0 kg/m², P=0.007). Adjusting for BMI, the risk of neonatal morbidity was reduced by 39.2% in G1 (CI: 0.39-0.92) and the risk of preterm birth was 2.0 times higher in G3 (CI: 1.1-3.7), compared to the remaining. There were no differences on the risk of large or small for gestational age, macrosomia or caesarean delivery between groups. The need for pharmacological treatment was inferior in G1 (P=0.002), and increased progressively across groups (36.9%< 40.9%< 63.5%). In multivariate analysis, the odd for requiring pharmacological treatment increased 6.0% per 1 mg/dl of FPG (CI: 1.02-1.10), 7.9% per year of maternal age (CI: 1.03-1.13) and 11.9% per 1 kg/m² of BMI (CI: 1.08-1.16), and was 80.6% higher in women with previous GD (CI: 1.07-3.06). Pharmacological treatment showed no association with pregnancy outcomes.

Conclusion: Screening in the first trimester was essential for the early diagnosis and treatment of a large proportion of GD. Women diagnosed by FPG of 92-94 mg/dl showed a lower risk of neonatal morbidity and a lesser need for pharmacological intervention, but suffered no evident harm from ongoing monitoring and treatment.