Using continuous glucose monitoring (CGM) to understand glucose control in women with obesity during pregnancy

In women with obesity but without diabetes, the factors driving poor pregnancy outcomes are inadequately understood. This study explores glucose as a potential mediator of adverse pregnancy outcomes in women with obesity. A two-arm observational study was conducted in a single maternity hospital in Melbourne, Australia. Thirty-eight women without diabetes, 20 of normal weight (BMI 20-24.9 kg/m²) and 18 with obesity (BMI ≥30 kg/m²), wore a continuous glucose monitor and had anthropometry and blood samples collected in early, mid and late pregnancy. Subjects who developed gestational diabetes were excluded prior to analysis. Groups were compared with respect to patient-day mean glucose, mean blood glucose, daytime and nighttime glucose AUC, post-prandial glucose AUC, HOMA-IR and QUICKI. Five subjects developed gestational diabetes and were excluded from the analysis. Compared to controls (n = 19), women with obesity (n = 14) had significantly higher PDMG (p < .001), daytime and nighttime glucose AUC (p < .01) and post-breakfast glucose AUC (p < .001 and p = .043) and post-dinner glucose AUC (p < .001) in early and mid-pregnancy. Mean plasma glucose and post-lunch glucose AUC were only higher in women with obesity in early pregnancy (p = .009 and p < .001, respectively). In mid and late pregnancy, HOMA-IR was significantly higher (p < .05) and QUICKI (p < .01) significantly lower in the women with obesity compared to controls. Most parameters that used to assess glycaemic control in pregnancy demonstrated significantly higher plasma glucose in women with obesity compared to controls. This supports the hypothesis that glucose is a mediator of adverse pregnancy outcomes in women with obesity.