Rationale and impact
These sections briefly explain why the committee made the recommendations and how they might affect practice.
There was evidence comparing continuous glucose monitoring with intermittently scanned CGM (isCGM, also commonly referred to as flash) and with intermittent capillary glucose monitoring, for pregnant women with type 1 diabetes.
When compared with intermittent capillary glucose monitoring, continuous glucose monitoring resulted in:
more women achieving their blood glucose targets
fewer caesarean sections
fewer neonatal intensive care unit (NICU) admissions.
One retrospective study was identified that compared flash with continuous glucose monitoring. This study showed no clear difference between the 2 monitoring systems in maternal and neonatal outcomes.
Health economic modelling found that flash clearly has the lowest overall cost of the 3 options. It is much less certain that flash provides the most benefit (a finding that is in line with the clinical evidence). The committee were concerned by the very low quality of the evidence for flash, the accuracy of flash (particularly in the hypoglycaemic range) and the number of finger-pricks that would still be needed to use flash safely.
The committee agreed that all the uncertainties in the evidence would be likely to lead to the benefits of flash being overestimated. Therefore, they could not be confident that flash represents a better use of NHS resources than continuous glucose monitoring, which had been shown in high-quality evidence to have better outcomes than intermittent capillary glucose monitoring and a 94% chance of being cheaper in the probabilistic sensitivity analysis.
Based on these findings, the committee recommended that continuous glucose monitoring should be offered to all women with type 1 diabetes to help women meet their pregnancy blood glucose targets and improve neonatal outcomes.
The committee also noted that some women may be unable to use continuous glucose monitoring or may prefer using flash instead. In these situations they recommended offering flash.
The committee amended the 2015 recommendation on considering continuous glucose monitoring for pregnant women who are on insulin therapy but do not have type 1 diabetes because they wanted to identify specific scenarios in which continuous glucose monitoring could be considered.
The committee believed that education and support are important for pregnant women using flash or continuous glucose monitoring, to ensure they get the full benefit. Therefore, they updated and expanded the 2015 recommendation on providing support.
Because of the weak evidence base comparing flash with continuous glucose monitoring in pregnant women with type 1 diabetes, the committee agreed that more evidence is needed on this, so they made a research recommendation.
The committee also reviewed the evidence for women who are planning a pregnancy. One study compared continuous glucose monitoring and intermittent capillary glucose monitoring, but it did not show a difference between these systems for important outcomes (such as achieving blood glucose targets). There was no evidence for flash glucose monitoring. Based on this lack of evidence, the committee did not make new recommendations for women who are planning a pregnancy. Instead, they recommended further research in this area.
Use of continuous glucose monitoring varies across the country, but most centres offer flash and/or continuous glucose monitoring to pregnant women with type 1 diabetes (in accordance with the NHS long-term plan). Because of this, the recommendations are unlikely to cause a major shift in practice.