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Continuous glucose monitoring metrics and birthweight: informing management of type 1 diabetes throughout pregnancy

posted on 13.06.2022, 14:32 authored by Eleanor M Scott, Helen R Murphy, Karl H Kristensen, Denice S Feig, Karin Kjölhede, Linda Englund-Ögge, Kerstin E Berntorp, Graham R Law


Objective: To determine gestational weekly changes in continuous glucose monitoring (CGM) metrics and 24hr glucose profiles, and their relationship to infant birthweight in pregnant women with type 1 diabetes.

Research Design and Methods: An analysis of >10.5 million CGM glucose measures from 386 pregnant women with type 1 diabetes, from two international, multicentre studies. CGM glucose metrics and 24hr glucose profiles were calculated for each gestational week and the relationship to normal (10-90th percentile) and large (>90th percentile) for gestational age (LGA) birthweight infants determined. 

Results: Mean CGM glucose concentration fell and percentage of time spent in the pregnancy target range 3.5-7.8 mmol/L (63-140mg/dL) increased in the first 10 weeks of pregnancy, plateaued until 28 weeks gestation, before further improvements in mean glucose and percentage time-in-range until delivery. The maternal CGM glucose metrics diverged at 10 weeks gestation, with significantly lower mean CGM glucose concentration (7.1mmol/L 95% CI 7.05-7.15 [127.8mg/dL 95% CI 126.9-128.7] vs.7.5mmol/L 95% CI 7.45-7.55 [135mg/dL 95% CI 134.1-135.9]) and higher percentage time-in-range (55% [95% CI 54-56] vs.50% [95% CI 49-51]) in women who had normal versus LGA. The 24hr glucose profiles were significantly higher across the day from 10 weeks gestation in LGA.

Conclusion: Normal birthweight is associated with achieving a significantly lower mean CGM glucose concentration across the 24-hour day and higher CGM time-in-range from before the end of the first trimester, emphasizing the need for a shift in clinical management, with increased focus on using weekly CGM glucose targets for optimising maternal glycemia from early pregnancy.


The CONCEPTT trial was funded by Juvenile Diabetes Research Foundation (JDRF) grants #17‐2011‐533, and grants under the JDRF Canadian Clinical Trial Network, a public‐private partnership including JDRF and FedDev Ontario and supported by JDRF #80‐2010‐585. Medtronic supplied the CGM sensors and CGM systems at reduced cost. GRL, EMS and HRM were part funded by HEFCE and MRC (MR/T001828/1). ES and HM were part funded by NIHR (EME 16/35/01), and HM was part funded by NIHR (CDF-2013-06-035). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research or the UK Department of Health. The Swedish study was funded by a research grant from Region Skåne, Sweden, and The Oak Foundation.