Do pregnant women with gestational diabetes need continuous glucose monitoring?

Abstract

BackgroundGestational diabetes mellitus affects 5–18% of pregnant women worldwide. Good blood glucose control is required to decrease the risk of macrosomia and long-term adverse effects for mothers and their offspring. Although continuous glucose monitoring (CGM) has been increasingly used for glucose management, little evidence has been reported in patients with gestational diabetes. We aimed to estimate and compare the effects of CGM parameters and routine oral glucose tolerance test (OGTT) measurements on fetal growth. MethodsIn this observational study, we recruited pregnant women with gestational diabetes who underwent CGM for 5–14 days after OGTT. We collected OGTT glucose measurements (including fasting, 1-h, and 2-h glucose concentrations), CGM time-series data, and birthweight. Parameters extracted from CGM data were glucose exposure metrics (including mean of day and night glucose and estimated HbA1c levels), glucose variability metrics (including J index and mean amplitude of glycaemic excursions), and a comprehensive glucose metric that captures both increasing mean glucose and glucose variability (ie, hours per day spent in severe glucose variability). We calculated birthweight percentiles using the INTERGROWTH-21st birthweight standard and used multiple linear regression models to estimate the association of birthweight percentile with OGTT measurements and CGM glucose features. We calculated adjusted mean difference and their 95% CIs for a 1 SD increase in glucose metrics. FindingsBetween Jan 11, 2017, and Nov 15, 2018, we enrolled 97 women with gestational diabetes. For OGTT measures, each 1 SD increase in maternal fasting glucose was associated with a 5·62 (95% CI 0·39–10·85) percentile increase in neonatal birthweight. Among CGM parameters, each 1 SD increase in mean glucose concentration at night and hours per day spent in severe glucose variability were associated with a 5·81 (95% CI 0·34–11·29) and 6·45 (0·73–12·17) percentile increase in birthweight. None of the levels of other glucose metrics either from OGTT or CGM measurements were associated with birthweight percentile. InterpretationFasting glucose has a comparable effect on fetal growth to glucose metrics obtained from CGM data, indicating that fasting glucose measurement is an effective and low-cost option for the management of gestational diabetes. FundingThe National Natural Science Foundation of China.