Based on the OR for macrosomia (> 4 kg), respiratory distress, preterm delivery and elective/emergency caesarean section reported in a recent meta-analysis for GDM women not using insulin, considering a relative precision of 50%, confidence level of 95%, and the rates of these outcomes resulted in this pilot study, a minimum sample size of 243 is required to explore the correlation of CGM data with at least one of these outcomes (caesarean section) (Additional file 4). Here, INS is linked to Large for gestational age.