CGM derived indicators of glycaemic control
A CGM (iPro2, Medtronic) was worn to continuously measure interstitial glucose concentrations across 7 days at 28- and 35-weeks gestation (Sept 2018 to July 2020; n= 57) and Freestyle Libre, Abbott (January 2022 to March 2022; n= 3) for 7 days at 28-30-, and 35-37 weeks’ gestation. The CGM was inserted into the subcutaneous layer on the posterior 1/3 of the upper limb. As per standard-care SMBG and calibration for iPro CGMs, women recorded capillary glucose concentrations four times daily and entered into the CareLink Pro App (discontinued) or provided a hard copy to researchers. Glycaemic variability [Mean Absolute Glucose (MAG) and SD] was analysed using the EasyGV spreadsheet (Oxford University, UK). Mean nocturnal glucose was calculated from 00:00 – 05:00 and 3 h postprandial glucose was calculated from main meal times. Incremental area under the curve (iAUC) was calculated using the trapezoid method.