Publication:

Neonatal outcomes in gestational diabetes mellitus: metformin alone versus metformin with insulin: a retrospective cohort study in India

Background Gestational diabetes mellitus (GDM) is associated with adverse neonatal outcomes, including increased neonatal intensive care unit (NICU) admissions and differences in birth weight. Although metformin is commonly used for glycemic control in GDM, some patients require adjunctive insulin therapy. Comparative data on neonatal outcomes between these regimens remain inadequate.

Methods This retrospective cohort study was conducted at a tertiary care center in Bengaluru, India. Medical records of women with singleton GDM pregnancies were analyzed and categorized into two groups: metformin monotherapy and metformin plus insulin. Primary outcomes were NICU admission and neonatal birth weight. Logistic regression was utilized to determine predictors of NICU admission, and linear regression estimated determinants of birth weight.

Results Among 123 GDM pregnancies, 52.8% received metformin alone and 47.2% received combination therapy. NICU admissions were significantly lower in the metformin group compared to the combination group (46.2% versus. 74.1%, p=0.002). After adjusting for gestational age, metformin monotherapy was associated with reduced odds of NICU admission (OR=0.41, p=0.032), though maternal HbA1C emerged as the strongest predictor (AUC=0.751). When both HbA1C and birth weight were included in the model, treatment regimen lost statistical significance (p=0.056). Neonatal birth weight was significantly lower in the combination group (mean difference -0.30 kg), with gestational age showing a stronger association (0.151 kg/week, p<0.001).

Conclusions Although NICU admissions were lower in the metformin monotherapy group, maternal glycemic control particularly HbA1C appears to be the principal determinant of neonatal outcomes in GDM pregnancies.