BACKGROUND AND PURPOSE:

1. Continuous glucose monitoring (CGM) provides contemporaneous glucose readings, thus allowing patients to adjust insulin in real-time
2. Data in non-pregnant women show benefit but conflicting data in pregnancy
3. Feig et al. (Lancet, 2017) determined the effectiveness of continuous glucose monitoring (CGM) on maternal glucose control compared to capillary glucose monitoring alone

METHODS:

• Multicenter, open-label, randomized controlled trial (2013-2016)
• 31 hospital centers in Canada, England, Scotland, Spain, Italy, Ireland, and the USA
• Women aged 18 to 40 years, with type 1 diabetes for a minimum of 1 year, receiving intensive insulin therapy, and pregnant or planning pregnancy
  • Live singleton fetus confirmed by ultrasound
  • ≤13 weeks and 6 days’ gestation
  • Pregnant: HbA1c between 6.5–10.0% (48–86 mmol/mol)
  • Planning for pregnancy: 7.0–10.0% (53–86 mmol/mol)
• Ran 2 trials in parallel for (1) pregnant and (2) planning pregnancy
• In both trials, participants were assigned to the following cohorts
  • Receive CGM in addition to capillary glucose monitoring
  • Receive capillary glucose monitoring
• Randomization was stratified by insulin delivery and baseline HbA1c
• Primary outcome was change in HbA1c
  • at 34 weeks’ gestation in pregnant participants
  • at 24 weeks for planning pregnancy participants
• Secondary outcomes included obstetric and neonatal health outcomes

RESULTS:

• 325 women were randomized
• When comparing pregnant CGM users to capillary monitored group, CGM users
  • had a slightly greater change in HbA_1c (mean difference -0.19%; 95% CI -0.34 to -0.03; p=0.0207)
  • Spent more time in target range (68% vs 61%; 0.0034)
  • Spent less time hyperglycemic range (27% vs 32%; p= 0.0279)
  • Had comparable hypoglycemic episodes
  • Spent comparable amount of time in hypoglycemic range (3% vs 4%, respectively)
• Neonatal outcomes in CGM users were significantly improved
  • Lower incidence of large for gestational age (odds ratio [OR] 0.51, 95% CI 0.28 – 0.90; p=0.0210)
  • Fewer NICU admissions lasting more than 24 h (OR 0.48; 95% CI 0.26 – 0.86; p=0.0157)
  • Fewer incidences of neonatal hypoglycemia (OR 0.45; 95% CI 0.22 to 0.89; p=0.0250)
  • 1-day shorter length of hospital stay (p=0.0091)
• There was no apparent benefit of CGM for women planning pregnancy
• CGM users had significantly more adverse skin reactions during trials (48% CGM vs 8% control during pregnancy; 44% CGM vs 9% control planning pregnancy)
• Data was generalizable across centers

CONCLUSION:

• CGM during pregnancy in patients with type 1 diabetes is linked to improved neonatal outcomes, likely because of better maternal glycemic control and reduced maternal hyperglycemia
• Number needed to treat (NNT) with CGM
  • 6 pregnant women NNT to prevent one NICU admission
  • 6 pregnant women NNT to prevent one large for gestational age
  • 8 pregnant women NNT to prevent one case of neonatal hypoglycemia
• The authors conclude that guidelines in type 1 diabetes in pregnancy should be revised to recommend offering CGM to pregnant women with type 1 diabetes using intensive insulin therapy in the first trimester

Learn More – Primary Sources:

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

Related ObG Topics:

Updated ACOG Guidance on Gestational Diabetes

Gestational Diabetes Mellitus – Definitions, Risk Factors and Complications

What Is The ‘One-Step’ GDM Screening Approach?

Screening for Gestational Diabetes: The ‘2 Step’ Approach