Glycemic, maternal and neonatal outcomes in women with type 1 diabetes using continuous glucose monitoring during pregnancy - Pump vs multiple daily injections, a secondary analysis of an observational cohort study

Introduction: Continuous glucose monitoring (CGM) provides detailed information about glucose level fluctuations over time. The method is increasingly being used in pregnant women with type 1 diabetes. However, only one previous study compared CGM results related to pregnancy outcomes in women using insulin pumps with those administering multiple daily injections (MDI). We performed a secondary analysis of CGM metrics from an observational cohort of pregnant women with type 1 diabetes and compared insulin pump and MDI therapies in relation to maternal and neonatal outcomes. Material and methods: The study included 185 pregnant Swedish women with type 1 diabetes undergoing CGM throughout pregnancy. Women were divided according to insulin administration mode, ie MDI (n = 131) or pump (n = 54). A total of 91 women used real-time CGM and 94 women used intermittently viewed CGM. Maternal demographics and maternal and neonatal outcome data were collected from medical records. CGM data were analyzed according to predefined glycemic indices: mean glucose; standard deviation; percentage of time within, below and above glucose target range; mean amplitude of glycemic excursion; high and low glucose indices; and coefficient variation in percent. Associations between insulin administration mode and CGM data, on the one hand, and maternal and neonatal outcomes, on the other, were analyzed with analysis of covariance and logistic regression, respectively, adjusted for confounders. Results: There were no differences in maternal characteristics or glycemic indices between the MDI and pump groups, except for a longer duration of type 1 diabetes and higher frequencies of microangiopathy and real-time CGM among pump users. Despite improvement with each trimester, glucose levels remained suboptimal throughout pregnancy in both groups. There were no differences between the MDI and pump groups concerning the respective associations with any of the outcomes. The frequency of large for gestational age was high in both groups (MDI 49% vs pump 63%) and did not differ significantly. Conclusions: Pregnant women with type 1 diabetes did not differ in glycemic control or pregnancy outcome, related to MDI or pump administration of insulin. Glycemic control remained suboptimal throughout pregnancy, regardless of insulin administration mode.