Trends in Gestational Diabetes Identified through Universal Screening: A Population‐Based Observational Study

OBJECTIVE: To explore trends of gestational diabetes (GDM) prevalence, as well as fasting, 1 h and 2 h post-load glucose and its determinants in Hungary between 2010 and 2017. DESIGN: Cross-sectional universal screening programme for GDM (3-point 75 g OGTT at 24-28 weeks of gestation). SETTING: Tolna County (South-Western Hungary). POPULATION: All singleton pregnancies between 2010 and 2017. METHODS: Participants with available co-variables (including 3-point OGTT) and deliveries ≥ 24 weeks of gestation were included (n = 7071, 88.4% of those eligible). Exposures (known GDM risk factors) were collected after delivery including BMI at early-pregnancy and at OGTT. MAIN OUTCOME MEASURES: Time trends of GDM occurrence (WHO-2013 diagnostic criteria) and fasting, 1 h, and 2 h post-load glucose. Analyses were done with multiple logistic and linear regression. RESULTS: The prevalence of GDM increased by 5% (95% CI: 4%-6%) from 15% to 20% between 2010 and 2017. Fasting, 1 h, and 2 h post-load glucose increased by 0.1 (95% CI 0.08-0.12), 0.5 (95% CI 0.4-0.6) and 0.2 (95% CI 0.1-0.3) mmol/l, respectively. On the basis of fully adjusted models including both BMI measures, a significant proportion (25%-30%) of this increase for GDM diagnosis and for fasting glucose was explained by increasing calendar trend in BMI measured at the OGTT. Smaller proportions of 1 h (12%) and 2 h (NS) post-load glucose were explained by BMI changes. CONCLUSIONS: Our finding suggests that BMI-gain during the first two trimesters of pregnancy is a more important determinant of the GDM epidemic in Hungary than early-pregnancy BMI. To prevent the further increase in the prevalence of GDM, both factors should be targeted.