Background
Gestational diabetes (GDM) is an increasingly common diagnosis globally, and in Australia complicates approximately 18% of pregnancies. GDM may lead to infants being born large for gestational age (LGA), and other complications. There is currently no consensus on optimal blood glucose level (BGL) treatment targets. This study aims to determine perinatal outcomes in patients with GDM when treated according to tighter or less tight BGL targets.
Methods
A retrospective cohort study including data from all 12 metropolitan hospitals in Victoria, Australia between January 2020 and December 2022. Women who gave birth to a term singleton infant and who had a diagnosis of GDM were included. Women were grouped by their hospitals fasting BGL targets: ‘tighter’ (< 5.2 mmol/L) or ‘less tight’ (< 5.5-5.6 mmol/L). The primary outcome was LGA; a range of secondary outcomes were compared. Inverse probability treatment weights were calculated based on sociodemographic and socioeconomic factors. We then
performed multilevel Poisson regression with delivery hospitals as random intercept.
Results
There were 25,041 births included, 12,423 (49.6%) in the ‘tighter’ target group, and 12,618 (50.4%) in the ‘less tight’ group. After adjusting for hospital and maternal demographics, there was no difference in LGA births (10.4% in ‘tighter’ vs 9.5% in ‘less tight’ (p=0.85)). More women received insulin treatment in the ‘tighter’ group (53%) compared to ‘less tight’ (35%, p<0.001). There were no significant differences in secondary outcomes.
Conclusion
Tighter BGL targets were not associated with improved perinatal outcomes, but were associated with an increase in pharmacotherapy.