Type 1 diabetes (T1DM) and obesity are both significant risk factors for adverse perinatal outcomes. Patients with T1DM often wear continuous glucose monitoring (CGM) devices and CGM metrics have been shown to predict adverse perinatal outcomes. Our research aimed to determine whether BMI would enhance the prediction of adverse perinatal outcomes.
A retrospective cohort study was conducted involving women with T1DM in pregnancy who were using CGM at Royal North Shore Hospital, Sydney. Women were categorised into 2 groups based on BMI at their first antenatal visit: normal weight (BMI 18.5 – 24.9 kg/m2) or overweight/obesity (BMI > 24.9 kg/m2). CGM metrics included average glucose, standard deviation, glucose management indicator, coefficient of variation (CV), time active, time in range (TIR), time above range (TAR) and time below range (TBR) at each trimester of pregnancy. Adverse maternal outcomes included gestational hypertension, pre-eclampsia, eclampsia, proteinuria, and post-partum haemorrhage, and adverse neonatal outcomes included preterm birth, large for gestational age (LGA), neonatal intensive care unit (NICU) admission, hypoglycaemia, jaundice, and fetal death in utero.
There was a significantly higher incidence of LGA neonates and NICU admissions in the overweight/obesity group as compared to the normal weight group. ROC curve analysis demonstrated that BMI improved the prediction of LGA when added to the two CGM metrics, CV and TBR, in trimester 1 and 2. Additionally, BMI improved the prediction of NICU admission when added to the CGM metrics including average glucose, GMI and TAR in trimester 3.
Our results showed that BMI improved the prediction of several adverse perinatal outcomes when added to CGM metrics, and highlights the importance of considering BMI as a predictor of adverse perinatal outcomes in pregnancies with T1DM. Further studies are required to determine whether BMI predicts other adverse perinatal outcomes.