LISBON -- Among pregnant women with type 1 diabetes, continuous glucose monitoring (CGM) was tied to better outcomes for mom and baby, researchers reported here.
Mothers who used CGM during pregnancy experienced less time overall in hyperglycemia compared to pregnant non-users of self monitoring blood glucose (27% versus 32%; P=0.0279), according to lead author Denice S. Feig, MD, of the University of Toronto, and colleagues.
Similarly, pregnant users spent more time in the recommended glucose control target range (63.1–140.5 mg/dL)(68% versus 61%; P=0.0034) throughout pregnancy.
The CONCEPTT trial's findings were presented at the European Association for the Study of Diabetes meeting and were also simultaneously published online in The Lancet.
Mothers weren't the only ones to benefit from CGM use. Neonates were less likely to be large for gestational age compared to those born to non-CGM mothers (OR 0.51, 95% CI 0.28-0.90; P=0.021). NICU hospital stays after delivery longer than 24 hours were also reduced among offspring of users (OR 0.48, 0.26-0.86; P=0.0157), as well as less risk of neonatal hypoglycemia (OR 0.45, 0.22-0.89; P=0.025).
Babies born to users on average also experienced 1 less day in the hospital (P=0.0091).
"The fact that CONCEPTT showed significant effects on the proportion of infants large for gestational age and on neonatal intensive care unit duration of stay with frequent CGM use is akin to studies in non-pregnant populations showing favourable outcomes with comparable CGM use," Satish K. Garg, MD, of the University of Colorado Denver and Sarit Polsky, MD, of UC Health in Aurora, wrote in an accompanying Lancet commentary.
He added that obstetric and endocrine medical societies should closely review these findings and should "consider advocating or recommending revising their guidelines accordingly."
Feig's group randomized a total of 325 women with type 1 diabetes from 31 hospitals in North America and Europe -- either currently pregnant or planning a pregnancy, assessed in separate, parallel trials -- into continuous capillary glucose monitoring or control. All women were currently treated with intensive insulin therapy with either an insulin pump or multiple daily injections. Exclusion criteria included severe nephropathy or other impeding illness.
A short run-in phase occurred prior to randomization during the open-label trial, in which all participants were required to wear a masked CGM for 6 days to collect overnight and daily glucose measures.
After 34 weeks of gestation, the researchers found a slight but statistically significant difference between groups regarding change in HbA1c from baseline, favoring CGM wearers (mean difference −0.19 percentage points, 95% CI −0.34 to −0.03; P=0.020). However, this finding wasn't robust enough to meet the prespecified threshold for a clinically worthwhile difference, which was set at 0.5 percentage points at 34 weeks gestation.
However, both pregnancy groups were similar regarding time spent in hypoglycemia (3% versus 4%, P=0.10), as well as severe hypoglycemic events (18 CGM, 21 control), which Garg and Polsky noted is "discouraging to see."
"We only need to treat 6 women with continuous glucose monitoring in order to prevent 1 baby who is LGA, 1 NICU admission, and we only need to treat 8 women with CGM to prevent 1 serious low blood glucose in the infant," Feig stated during a press conference.
Among the pregnant participants, serious adverse events were comparable between groups (7% CGM, 5% control), while overall adverse events were only slightly higher in among users, mainly due to skin reactions (48%, 40% control).
"Looking a little bit further, we'd like to identify the women who didn't benefit, so that we could target even more advanced artificial pancreas or closed loop treatment to the group of women who might need it most," said senior study author Helen R. Murphy, MD, of the University of East Anglia in the U.K., during a press conference.
Continuous glucose monitoring in pregnant women with type 1 diabetes (CONCEPTT): a multicentre international randomised controlled trial
Pregnant 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.
In 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, number NCT01788527.
Between 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 common adverse events were skin reactions occurring in 49 (48%) of 103 CGM participants and eight (8%) of 104 control participants during pregnancy and in 23 (44%) of 52 CGM participants and five (9%) of 57 control participants in the planning pregnancy trial. The most common serious adverse events were gastrointestinal (nausea and vomiting in four participants during pregnancy and three participants planning pregnancy).
Use of CGM during pregnancy in patients with type 1 diabetes is associated with improved neonatal outcomes, which are likely to be attributed to reduced exposure to maternal hyperglycaemia. CGM should be offered to all pregnant women with type 1 diabetes using intensive insulin therapy. This study is the first to indicate potential for improvements in non-glycaemic health outcomes from CGM use.
Juvenile Diabetes Research Foundation, Canadian Clinical Trials Network, and National Institute for Health Research.
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