Early screening and diagnosis of gestational diabetes mellitus (GDM) and its impact on perinatal outcomes

Aims

To compare the maternal and neonatal outcomes following early diagnosis compared with routine diagnosis of gestational diabetes (GDM).

Methods

In this observational study, 3494 women were categorised by weeks of gestation at GDM diagnosis: early GDM (≤20 weeks) and routine GDM (>20 weeks). The early GDM group was further divided by treatment commencement as immediate (<12 weeks) and delayed (12–20 weeks) and by diagnostic fasting blood glucose as higher-FBG (5.3–6.0 mmol/L) and lower-FBG group (FBG 5.1–5.2 mmol/L). Primary outcomes were large for gestational age (LGA) and small for gestational age (SGA). Generalized linear models used to calculate risk ratios and adjusted for confounding.

Results

Risk ratios (RR) for LGA and SGA were similar for early versus routine diagnosis, and immediate versus delayed treatment. The higher-FBG immediate treatment group had a lower risk of newborn respiratory distress (RR 0.52, 95 %CI 0.34, 0.81) and emergency caesarean (RR 0.55, 95 %CI 0.34, 0.88) compared to the higher-FBG delayed treatment group. Among the lower-FBG group, no such benefits were seen.

Conclusions

Fasting glucose levels modified the effects of early treatment of GDM where a higher-FBG with immediate treatment appears to reduce perinatal complications, but treating women with lower-FBG early has no benefits.