Continuous glucose monitoring in pregnant women with type 1 diabetes (CONCEPTT): a multicentre international randomised controlled trial

Denice S. Feig, Lois E. Donovan, Rosa Corcoy, Kellie E. Murphy, Stephanie A. Amiel, Katharine F. Hunt, Elizabeth Asztalos, Jon F.R. Barrett, J. Johanna Sanchez, Alberto de Leiva, Moshe Hod, Lois Jovanovic, Erin Keely, Ruth McManus, Eileen K. Hutton, Claire L. Meek, Zoe A. Stewart, Tim Wysocki, Robert O'Brien, Katrina RuedyGeorge Tomlinson, Craig Kollman, Helen R. Murphy, CONCEPTT Collaborative Group, Helen R. Murphy, Jeannie Grisoni, Carolyn Byrne, Sandra Neoh, Katy Davenport, Lois E. Donovan, Claire Gougeon, Carolyn Oldford, Catherine Young, Stephanie Amiel, Katharine F. Hunt, Louisa Green, Helen Rogers, Benedetta Rossi, Denice Feig, Barbara Cleave, Michelle Strom, Rosa Corcoy, Alberto de Leiva, Juan María Adelantado, Ana Isabel Chico, Diana Tundidor, Erin Keely, Janine Malcolm, Kathy Henry, Damian Morris, Gerry Rayman, Duncan Fowler, Susan Mitchell, Josephine Rosier, Rosemary Temple, Jeremy Turner, Gioia Canciani, Niranjala Hewapathirana, Leanne Piper, Ruth McManus, Anne Kudirka, Margaret Watson, Matteo Bonomo, Basilio Pintaudi, Federico Bertuzzi, Giuseppina Daniela, Elena Mion, Julia Lowe, Ilana Halperin, Anna Rogowsky, Sapida Adib, Robert Lindsay, David Carty, Isobel Crawford, Fiona Mackenzie, Therese McSorley, John Booth, Natalia McInnes, Ada Smith, Irene Stanton, Tracy Tazzeo, John Weisnagel, Peter Mansell, Nia Jones, Gayna Babington, Dawn Spick, Malcolm MacDougall, Sharon Chilton, Terri Cutts, Michelle Perkins, Eleanor Scott, Del Endersby, Anna Dover, Frances Dougherty, Susan Johnston, Simon Heller, Peter Novodorsky, Sue Hudson, Chloe Nisbet, Thomas Ransom, Jill Coolen, Darlene Baxendale, Richard Holt, Jane Forbes, Nicki Martin, Fiona Walbridge, Fidelma Dunne, Sharon Conway, Aoife Egan, Collette Kirwin, Michael Maresh, Gretta Kearney, Juliet Morris, Susan Quinn, Rudy Bilous, Rasha Mukhtar, Ariane Godbout, Sylvie Daigle, Alexandra Lubina, Margaret Jackson, Emma Paul, Julie Taylor, Robyn Houlden, Adriana Breen, Anita Banerjee, Anna Brackenridge, Annette Briley, Anna Reid, Claire Singh, Jill Newstead-Angel, Janet Baxter, Sam Philip, Martyna Chlost, Lynne Murray, Kristin Castorino, Donna Frase, Lois Jovanovic, Olivia Lou, Marlon Pragnell

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500 Citations (Scopus)


Background 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. Methods 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. Findings 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). Interpretation 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.

Original languageEnglish
Pages (from-to)2347-2359
Number of pages13
JournalThe Lancet
Issue number10110
Publication statusPublished - 25 Nov 2017


  • glucose monitoring
  • Type 1 diabetes
  • Diabetes in pregnancy
  • randomised controlled trial
  • maternal hyperglycaemia
  • neonatal outcomes


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