Metformin is a potential alternative to insulin therapy for Gestational Diabetes Mellitus (GDM), however controversy still exists regarding its optimal use and relative therapeutic benefit. The aim of this study was to determine maternal characteristics associated with pharmacotherapy choice and relationships with maternal and fetal outcomes.
This retrospective, cohort study included women with GDM attending Royal North Shore Hospital from 2010 to 2017. Maternal characteristics, pharmacotherapy, and maternal and fetal outcomes were extracted from electronic medical records. Univariate and multivariate analyses were undertaken using SPSS v24.
Of 540 women with GDM (age 33.8 ± 4.5 years, BMI 25.3 ± 5.8kg/m2, parity 1.7 ± 0.8, gestational age at GDM diagnosis 25.5 ± 5.8 weeks), 269 (49.8%) were managed with diet and lifestyle modification alone, 166 (30.7%) with insulin, 64 (11.9 %) with metformin and 41 (7.6%) with combination metformin and insulin.
Women managed with diet/lifestyle had lower BMI compared to other groups (p < 0.005). Higher BMI was predictive of metformin use in the diet group (p <0.05), and supplemental therapy in the metformin group (p < 0.05). Earlier diagnosis of GDM was predictive of metformin therapy (p < 0.005). Women diagnosed later in pregnancy were less likely to require pharmacotherapy (p < 0.05). Higher fasting blood glucose at diagnosis was indicative of need for pharmacotherapy (p < 0.05). Women requiring combination metformin and insulin were older (p < 0.01), with higher BMI, and greater parity (both p < 0.05). There was no difference in adverse maternal or fetal outcomes between groups.
Our data indicate that early-pregnancy BMI, gestational age at GDM diagnosis, and fasting blood glucose level on OGTT are significant predictors of the requirement for pharmacotherapy. Maternal and fetal outcomes were similar regardless of therapeutic choice, suggesting that treating to target glucose levels confers maternal and fetal benefit irrespective of the agent chosen.