NIHR Signal Fewer large babies are born to pregnant woman with type 1 diabetes if their glucose was monitored continuously

Published on 12 December 2017

Pregnant women with type 1 diabetes who used a continuous glucose monitoring system were half as likely to have a large baby compared with those using standard finger prick blood glucose measurements. Only 15% of infants needed intensive care admissions due to low blood glucose in the continuous glucose monitoring group, compared with 28% born to mothers in the standard finger prick control group.

Pregnant women using continuous monitoring spent 7% more time in the target glucose range than those on standard measurements. However, their HbA1c levels, which indicate diabetic control over 12 weeks, only improved slightly. This may be unsurprising because HbA1c results are less reliable in pregnancy and women found it hard to stick to the continuous monitoring protocol.

Strict control of blood glucose levels during pregnancy reduces the risk for women with type 1 diabetes, and their babies are less likely to be large or need treatment for low blood glucose. Continuous monitoring provides many readings but requires the user to deliver insulin accordingly. Motivated women may find continuous monitoring helps them manage their glucose levels more closely during pregnancy and reduce both antenatal and postnatal complications.

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Why was this study needed?

Up to 5% of women giving birth in England and Wales, each year have diabetes. Of these, 7.5% have type 1 diabetes.

Women with type 1 diabetes are at higher risk of complications in pregnancy mainly because glucose levels are harder to control. Their babies are more likely to be larger than average, which can mean a difficult delivery, and need special care when born. The cost of a baby’s neonatal intensive care stay is £1,118 per day in the UK. 

A continuous glucose monitoring system gives multiple glucose readings, day and night, via a sensor placed under the skin. It is different to an insulin pump, which delivers the drug. Continuous monitoring provides more data than finger prick blood glucose measurements.

Previous studies recruited low numbers and provided weak evidence, so the authors wanted to design a larger study. This study aimed to see if pregnant women on insulin could control their blood sugar levels better using these devices and if there was an improvement in maternal and newborn health outcomes.

What did this study do?

This randomised controlled trial, CONCEPTT, took place in 31 hospitals in seven high-income countries, including England and Scotland.

Pregnant women with type 1 diabetes (215) and women planning to get pregnant (110), in separate groups, were randomised to use continuous glucose monitoring or finger prick glucose monitoring.

Diabetes teams trained participants to use the continuous monitoring devices. Both groups were instructed to take at least seven finger prick readings per day; the intervention group did this to verify the machine readings before administering insulin.

Nearly half of pregnant participants used an insulin pump instead of multiple injections. In the UK, only 6% of non-pregnant people with type 1 diabetes use insulin pumps. The groups were treated equally; however, there were more unscheduled nurse visits in the intervention group due to technical problems.

What did it find?

  • Pregnant women using continuous glucose monitoring had lower HbA1c levels at 34 weeks. Levels decreased from 51mmol/mol (6.83%) at baseline to 46mmol/mol (6.35%) at 34 weeks of pregnancy, compared to the control group, which dropped from 52mmol/mol (6.95%) to 48mmol/mol (6.53%). This indicates a slightly better control of blood glucose levels for women using continuous monitoring. There was no significant difference in change of HbA1c levels in the planning pregnancy groups.
  • Pregnant women at 34 weeks of pregnancy using continuous monitoring spent more of their time, 68% (which equates to one hour 41 minutes more per day), in the recommended glucose control range of 3.5 to 7.8 mmol/L compared to those in the control group who spent 61% of the time in the target glucose control range. At baseline, both groups spent 52% in target glucose control range.
  • Newborns were less likely to be larger than average if they were born to mothers using continuous monitoring than to mothers who used finger prick blood glucose monitoring only (odds ratio [OR] 0.51, 95% CI 0.28 to 0.90). Rates were high in both groups though, with 36% of babies born in the continuous monitoring group extremely large for gestational age compared to 44% in the standard group. They were also less likely to be admitted to neonatal intensive care for more than 24 hours, 27% admitted compared to 43% (OR 0.48, 95% CI 0.26 to 0.86). Fewer newborns born to this group experienced a drop in blood glucose that needed treatment, 15% versus 28% (OR 0.45, 0.22 to 0.89).
  • There were no significant differences between the groups for patient-reported outcomes such as quality of life.
  • There were 109 adverse events experienced by 107 women randomised to continuous monitoring and 78 adverse events experienced by 107 women in the control group (relative risk [RR] 1.4, 95% CI 1.0 to 1.8). The most common events were skin reactions and problems with the continuous monitoring device. Few significant serious adverse events took place. Sticking to the continuous monitoring protocol appeared to be difficult for women as 30% of pregnant women did not achieve it more than 75% of the time.

What does current guidance say on this issue?

NICE 2008 guidance recommends that clinicians do not offer continuous glucose monitoring routinely to pregnant women with diabetes. It advises to consider it for some pregnant women taking insulin. This includes pregnant women on insulin therapy who have unstable blood glucose levels or have problems with severe low blood glucose episodes.

What are the implications?

Improved newborn health outcomes with continuous glucose monitoring are probably due to better glucose control in pregnancy.

There could be a role for continuous monitoring use by pregnant women with type 1 diabetes, but this may depend on individual preferences. Participants selected for this trial are likely to be more motivated than average because they had to meet eligibility criteria for using continuous monitoring consistently. Device placement can also irritate skin, and continuous readings may heighten anxiety.

Economic analyses are needed to justify the costs of the system and trained support required. There is scope for further patient outcome results which may help inform patient choice.

Citation and Funding

Feig DS, Donovan LE, Corcoy R, et al; CONCEPTT Collaborative Group. Continuous glucose monitoring in pregnant women with type 1 diabetes (CONCEPTT): a multicentre international randomised controlled trial. Lancet. 2017;390(10110):2347-59.

This project was funded by the National Institute for Health Research, Juvenile Diabetes Research Foundation and Canadian Clinical Trials Network.

Bibliography

Diabetes UK. HbA1c calculator. London; Diabetes UK. Accessed 2017.

Diabetes UK. Continuous Glucose Monitoring. London; Diabetes UK. Accessed 2017.

NHS Choices. Type 1 diabetes. Department of Health: London; 2016

NICE. Diabetes in pregnancy: management from preconception to the postnatal period. NG3. London: National Institute for Health and Care Excellence; 2015.

NICE. Costing statement: Diabetes in pregnancy. London: National Institute for Health and Care Excellence; 2015.

Why was this study needed?

Up to 5% of women giving birth in England and Wales, each year have diabetes. Of these, 7.5% have type 1 diabetes.

Women with type 1 diabetes are at higher risk of complications in pregnancy mainly because glucose levels are harder to control. Their babies are more likely to be larger than average, which can mean a difficult delivery, and need special care when born. The cost of a baby’s neonatal intensive care stay is £1,118 per day in the UK. 

A continuous glucose monitoring system gives multiple glucose readings, day and night, via a sensor placed under the skin. It is different to an insulin pump, which delivers the drug. Continuous monitoring provides more data than finger prick blood glucose measurements.

Previous studies recruited low numbers and provided weak evidence, so the authors wanted to design a larger study. This study aimed to see if pregnant women on insulin could control their blood sugar levels better using these devices and if there was an improvement in maternal and newborn health outcomes.

What did this study do?

This randomised controlled trial, CONCEPTT, took place in 31 hospitals in seven high-income countries, including England and Scotland.

Pregnant women with type 1 diabetes (215) and women planning to get pregnant (110), in separate groups, were randomised to use continuous glucose monitoring or finger prick glucose monitoring.

Diabetes teams trained participants to use the continuous monitoring devices. Both groups were instructed to take at least seven finger prick readings per day; the intervention group did this to verify the machine readings before administering insulin.

Nearly half of pregnant participants used an insulin pump instead of multiple injections. In the UK, only 6% of non-pregnant people with type 1 diabetes use insulin pumps. The groups were treated equally; however, there were more unscheduled nurse visits in the intervention group due to technical problems.

What did it find?

  • Pregnant women using continuous glucose monitoring had lower HbA1c levels at 34 weeks. Levels decreased from 51mmol/mol (6.83%) at baseline to 46mmol/mol (6.35%) at 34 weeks of pregnancy, compared to the control group, which dropped from 52mmol/mol (6.95%) to 48mmol/mol (6.53%). This indicates a slightly better control of blood glucose levels for women using continuous monitoring. There was no significant difference in change of HbA1c levels in the planning pregnancy groups.
  • Pregnant women at 34 weeks of pregnancy using continuous monitoring spent more of their time, 68% (which equates to one hour 41 minutes more per day), in the recommended glucose control range of 3.5 to 7.8 mmol/L compared to those in the control group who spent 61% of the time in the target glucose control range. At baseline, both groups spent 52% in target glucose control range.
  • Newborns were less likely to be larger than average if they were born to mothers using continuous monitoring than to mothers who used finger prick blood glucose monitoring only (odds ratio [OR] 0.51, 95% CI 0.28 to 0.90). Rates were high in both groups though, with 36% of babies born in the continuous monitoring group extremely large for gestational age compared to 44% in the standard group. They were also less likely to be admitted to neonatal intensive care for more than 24 hours, 27% admitted compared to 43% (OR 0.48, 95% CI 0.26 to 0.86). Fewer newborns born to this group experienced a drop in blood glucose that needed treatment, 15% versus 28% (OR 0.45, 0.22 to 0.89).
  • There were no significant differences between the groups for patient-reported outcomes such as quality of life.
  • There were 109 adverse events experienced by 107 women randomised to continuous monitoring and 78 adverse events experienced by 107 women in the control group (relative risk [RR] 1.4, 95% CI 1.0 to 1.8). The most common events were skin reactions and problems with the continuous monitoring device. Few significant serious adverse events took place. Sticking to the continuous monitoring protocol appeared to be difficult for women as 30% of pregnant women did not achieve it more than 75% of the time.

What does current guidance say on this issue?

NICE 2008 guidance recommends that clinicians do not offer continuous glucose monitoring routinely to pregnant women with diabetes. It advises to consider it for some pregnant women taking insulin. This includes pregnant women on insulin therapy who have unstable blood glucose levels or have problems with severe low blood glucose episodes.

What are the implications?

Improved newborn health outcomes with continuous glucose monitoring are probably due to better glucose control in pregnancy.

There could be a role for continuous monitoring use by pregnant women with type 1 diabetes, but this may depend on individual preferences. Participants selected for this trial are likely to be more motivated than average because they had to meet eligibility criteria for using continuous monitoring consistently. Device placement can also irritate skin, and continuous readings may heighten anxiety.

Economic analyses are needed to justify the costs of the system and trained support required. There is scope for further patient outcome results which may help inform patient choice.

Citation and Funding

Feig DS, Donovan LE, Corcoy R, et al; CONCEPTT Collaborative Group. Continuous glucose monitoring in pregnant women with type 1 diabetes (CONCEPTT): a multicentre international randomised controlled trial. Lancet. 2017;390(10110):2347-59.

This project was funded by the National Institute for Health Research, Juvenile Diabetes Research Foundation and Canadian Clinical Trials Network.

Bibliography

Diabetes UK. HbA1c calculator. London; Diabetes UK. Accessed 2017.

Diabetes UK. Continuous Glucose Monitoring. London; Diabetes UK. Accessed 2017.

NHS Choices. Type 1 diabetes. Department of Health: London; 2016

NICE. Diabetes in pregnancy: management from preconception to the postnatal period. NG3. London: National Institute for Health and Care Excellence; 2015.

NICE. Costing statement: Diabetes in pregnancy. London: National Institute for Health and Care Excellence; 2015.

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

Published on 20 September 2017

Feig, D. S.,Donovan, L. E.,Corcoy, R.,Murphy, K. E.,Amiel, S. A.,Hunt, K. F.,Asztalos, E.,Barrett, J. F. R.,Sanchez, J. J.,de Leiva, A.,Hod, M.,Jovanovic, L.,Keely, E.,McManus, R.,Hutton, E. K.,Meek, C. L.,Stewart, Z. A.,Wysocki, T.,O'Brien, R.,Ruedy, K.,Kollman, C.,Tomlinson, G.,Murphy, H. R.

Lancet , 2017

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 ClinicalTrials.gov, 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. FUNDING: Juvenile Diabetes Research Foundation, Canadian Clinical Trials Network, and National Institute for Health Research.

Continuous glucose monitoring systems are small devices worn just underneath the skin and measure glucose levels every few minutes. There are different types of devices available. Either they measure glucose levels in real time with the user being able to check the devices anytime, or they store the results and the user, or healthcare professional, can download the data and look back at the results to see trends. A continuous monitoring device has to be calibrated using finger prick blood glucose levels usually at least twice a day. The device is changed every seven days. The sensor does not deliver insulin.

Expert commentary

Women with type 1 diabetes want to have a healthy baby, but face considerably increased problems for the baby. This study points a way forward.

The effect size of continuous glucose monitoring was large – halving the incidence of large-for-gestational-age babies, neonatal hypoglycaemia rate and prolonged neonatal intensive care units stay.

The findings from this well-designed study can immediately be implemented. A new, simpler generation of devices, flash meters, are available for provision by the NHS.

Although the impact of introducing continuous monitoring in type 1 diabetic pregnancy requires monitoring, there is no reason not to act now.

Roy Taylor, Professor of Medicine & Metabolism, Newcastle University; Honorary Consultant Physician, Newcastle Hospitals NHS Foundation Trust