Continuous glucose monitoring feedback in the subsequent development of gestational diabetes: a randomised controlled trial in pregnant women

Objective: To examine CGM feedback with the subsequent development of gestational diabetes (GDM), maternal glycaemic control, and glycaemic variability during pregnancy with randomisation 1:1 with one study arm receiving CGM feedback by intermittent scanning (unblinded group), versus masked feedback (blinded group). Design: Prospective, single-center, randomized controlled trial Setting: Single tertiary care hospital Population: Pregnant women recruited in the first trimester of pregnancy Methods: We assessed GDM and plasma glucose levels diagnosed by the 75-g oral glucose tolerance test (OGTT) at 24-28 weeks as a primary outcome. The secondary outcome was CGM-derived parameters of glycaemic variability across the first (9-13 weeks), second (18-23 weeks), late second and early third (24-31 weeks) and third trimester (32-33weeks). Results: Over 47 months, 206 pregnant women were enrolled at 9-13 weeks. There were no significant differences with GDM outcomes, fasting, 1-hour or 2-hour plasma glucose concentrations between study arms. The unblinded group had higher %time-in-range in the first (83.2% vs 78.1%; p=0.06), second [88.7% vs 80.5%; p=0.02] and third trimester (90.2% vs 79.5%; p=0.07), compared to the blinded group. Conversely, the unblinded group had lower %time-below-range in the first trimester (15.4% vs 21.2%; p=0.06), and early second trimester (8.8% vs 16.9%; p=0.05]. No significant differences were observed with the %time-above-range, mean, standard deviation, Mean Amplitude Glycaemic Excursion and % Coefficient Variation across all trimesters. Conclusion : CGM feedback, coupled with better glycaemic control (higher %TIR and low %TBR) indicates its’ potential use in combination with appropriate patient education for promoting better glucose control during pregnancy.