Background: Pregnant women with type 1 diabetes are highly motivated to attain optimal glucose control, but neonatal outcomes attributed to maternal hyperglycaemia remain suboptimal. The aim of CONCEPTt was to examine the effectiveness of Continuous Glucose Monitoring (CGM) on glucose control, obstetric and neonatal health outcomes.
Methods: In a multicentre, open-label, randomised controlled trial, we randomised 325 women with type 1 diabetes (215 pregnant, 110 planning pregnancy) using intensive insulin therapy, to capillary glucose monitoring with or without CGM. Randomisation was stratified by insulin delivery (pump or injections) and baseline HbA1c. The primary outcome was change in HbA1c from randomisation to 34 weeks gestation in pregnant women, and to 24 weeks or conception in women planning pregnancy. Secondary outcomes included percentage time-in-target (3.5-7.8 mmol/L), patient-reported outcome measures, obstetric and neonatal health outcomes.
Results: There were clinically small differences in HbA1c, in pregnant women using CGM (mean difference -0.19%; CI95% -0.34 to -0.03%; p=0.02). Pregnant CGM users spent more time-in-target (68 vs 61%; p=0.0034) and less time hyperglycaemic (27 vs 32%; p=0.028) with comparable severe hypoglycaemia episodes and time spent hypoglycaemic. Their neonatal outcomes were significantly improved, with lower incidence of large for gestational age, less neonatal hypoglycaemia and 1-day shorter length of hospital stay. There was no apparent benefit of CGM in women planning pregnancy.
Conclusion: Use of CGM during type 1 diabetes pregnancy is associated with improved neonatal outcomes, attributed to reduced exposure to maternal hyperglycaemia.