SummaryBackgroundPregnant women with type 1 diabetes are a high-risk population who are recommended to strive for optimal glucose control, but neonatal outcomes attributed to maternal hyperglycaemia remain suboptimal. Our aim was to examine the effectiveness of continuous glucose monitoring (CGM) on maternal glucose control and obstetric and neonatal health outcomes.MethodsIn this multicentre, open-label, randomised controlled trial, we recruited women aged 18–40 years with type 1 diabetes for a minimum of 12 months who were receiving intensive insulin therapy. Participants were pregnant (≤13 weeks and 6 days' gestation) or planning pregnancy from 31 hospitals in Canada, England, Scotland, Spain, Italy, Ireland, and the USA. We ran two trials in parallel for pregnant participants and for participants planning pregnancy. In both trials, participants were randomly assigned to either CGM in addition to capillary glucose monitoring or capillary glucose monitoring alone. Randomisation was stratified by insulin delivery (pump or injections) and baseline glycated haemoglobin (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, and was assessed in all randomised participants with baseline assessments. Secondary outcomes included obstetric and neonatal health outcomes, assessed with all available data without imputation. This trial is registered with ClinicalTrials.gov, number NCT01788527.FindingsBetween March 25, 2013, and March 22, 2016, we randomly assigned 325 women (215 pregnant, 110 planning pregnancy) to capillary glucose monitoring with CGM (108 pregnant and 53 planning pregnancy) or without (107 pregnant and 57 planning pregnancy). We found a small difference in HbA1c in pregnant women using CGM (mean difference −0·19%; 95% CI −0·34 to −0·03; p=0·0207). Pregnant CGM users spent more time in target (68% vs 61%; p=0·0034) and less time hyperglycaemic (27% vs 32%; p=0·0279) than did pregnant control participants, with comparable severe hypoglycaemia episodes (18 CGM and 21 control) and time spent hypoglycaemic (3% vs 4%; p=0·10). Neonatal health outcomes were significantly improved, with lower incidence of large for gestational age (odds ratio 0·51, 95% CI 0·28 to 0·90; p=0·0210), fewer neonatal intensive care admissions lasting more than 24 h (0·48; 0·26 to 0·86; p=0·0157), fewer incidences of neonatal hypoglycaemia (0·45; 0·22 to 0·89; p=0·0250), and 1-day shorter length of hospital stay (p=0·0091). We found no apparent benefit of CGM in women planning pregnancy. Adverse events occurred in 51 (48%) of CGM participants and 43 (40%) of control participants in the pregnancy trial, and in 12 (27%) of CGM participants and 21 (37%) of control participants in the planning pregnancy trial. Serious adverse events occurred in 13 (6%) participants in the pregnancy trial (eight [7%] CGM, five [5%] control) and in three (3%) participants in the planning pregnancy trial (two [4%] CGM and one [2%] control). The most...

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OBJECTIVEWomen with diabetes in pregnancy have high rates of pregnancy complications. Our aims were to explore trends in the incidence of diabetes in pregnancy and examine whether the risk of serious perinatal outcomes has changed. RESEARCH DESIGN AND METHODSWe performed a population-based cohort study of 1,109,605 women who delivered in Ontario, Canada, between 1 April 1996 and 31 March 2010. We categorized women as gestational diabetes (GDM) (n = 45,384), pregestational diabetes (pre-GDM) (n = 13,278), or no diabetes (n = 1,050,943). The annual age-adjusted rates of diabetes in pregnancy were calculated, and rates of serious perinatal outcomes were compared between groups and by year using Poisson regression. RESULTSThe age-adjusted rate of both GDM (2.7-5.6%, P < 0.001) and pre-GDM (0.7-1.5%, P < 0.001) doubled from 1996 to 2010. The rate of congenital anomalies declined by 23%, whereas the rate of perinatal mortality did not change significantly. However, compared with women with no diabetes, women with pre-GDM and GDM faced an increased risk of congenital anomalies (relative risk 1.86 [95% CI 1.49-2.33] and 1.26 [1.09-1.45], respectively), and perinatal mortality remained elevated in women with pre-GDM (2.33 [1.59-3.43]). CONCLUSIONSThe incidence of both GDM and pre-GDM in pregnancy has doubled over the last 14 years, and the overall burden of diabetes in pregnancy on society is growing. Although congenital anomaly rates have declined in women with diabetes, perinatal mortality rates remain unchanged, and the risk of both remains significantly elevated compared with nondiabetic women. Increased efforts are needed to reduce these adverse outcomes.Diabetes in pregnancy is becoming an increasingly growing concern as the prevalence of diabetes continues to rise (1). Women with diabetes who become pregnant have an increased risk of pregnancy complications (2-7), including serious perinatal outcomes such as stillbirth, perinatal mortality, and major congenital malformations. Hyperglycemia in the period around conception and the first weeks