National Gestational Diabetes Mellitus Audit

Gestational diabetes mellitus (GDM) is the most common medical condition to affect pregnant women. If it is untreated during pregnancy it can led to poor maternal and neonatal outcomes. However, effective treatment substantially reduces these risks and should lead to successful pregnancy outcomes. Management of GDM is clearly outlined in NICE Guidance NG3. 

Clinical teams looking after women with diabetes in pregnancy report ever increasing numbers of women developing GDM, with a disproportionate impact on women of colour and those living in deprived communities. However, the true scale of the problem is unknown as there is no national data collection to determine how many women are diagnosed with GDM and whether healthcare inequalities are being addressed.

There is growing concern that the large numbers of women developing GDM are putting increased demand on clinical services and that this could be adversely affecting pregnancy outcomes. It is not currently known what the maternal and neonatal outcomes are for women with GDM to be able to assess this over time and ensure that all services are providing high quality care.

Women who have GDM are at high risk of developing diabetes and cardiovascular disease after pregnancy. They need long term follow up to assess and manage these risks, including referral for support to reduce the development of diabetes, for example Diabetes Prevention Programme. NICE NG3 and NICE Quality Standards for Diabetes in Pregnancy (QS109) emphasise how important it is that women are being adequately supported postnatally to detect and prevent the development of diabetes, but it is not known whether this is happening in practice. 

Essentially there are no national data to measure whether the provision of GDM care is in line with NICE recommendations either across diabetes maternity specialist services or in primary care.

Consideration will include:

• diagnosis of GDM
• ethnicity
• deprivation quintile
• parity
• BMI
• smoking

Outcomes include:

• pre-eclampsia/hypertension
• onset of labour
• mode of delivery
• sex of baby
• birthweight
• gestational age at birth
• NICU admission
• perinatal outcome, including 28 day mortality

Links to the following will be established:

• National Diabetes Audit data for assessing risk of development of diabetes
• Diabetes Prevention Programme data to assess number of referrals after pregnancy
• GP record to assess whether women are receiving annual HbA1c and detection of cardiometabolic disease

In 2021 a feasibility study was undertaken by the audit team at NHS England to see if it was possible to collect data on women with GDM to enable the measurement of a number of key quality metrics relating to their care and outcomes for both mother and baby.

As GDM is reported to affect between 10 to 20% of pregnant women it was recognised that it would not be feasible to collect this mandatory data by completing individual patient questionnaires like the National Pregnancy in Diabetes (NPID) audit, as  the burden on service providers would be too high. 

Instead, data that is routinely collected for maternity services nationally via the Maternity Services Data Set (MSDS) and linkage with other existing NHS datasets, is being utilised. The feasibility study showed that the MSDS has the potential to generate much of the data required but is still immature. Data quality for diagnosis of GDM and some key maternal and neonatal characteristics were suboptimal but demographic characteristics and pregnancy outcomes were well recorded. It was agreed that the GDM audit could be derived from this existing database with minimal burden on NHS staff/services.

The National GDM Audit has been funded for 3 years as part of the National Diabetes Audit (NDA) Programme; 2022/23 was the first year. The focus on the first and second year was to raise awareness of the audit and to engage with maternity services to encourage improved completion of the data items required in the MSDS. The third year has been used to add data from general practices to the collection and the necessary approvals that go with this.

In late 2025 GDM data outputs will be made available for services to see their performance in the key metrics relating to GDM. 

This is a mandatory national audit as part of the NDA, so all services seeing women with GDM must participate. Data collection is through the MSDS. The key data item not currently well collected is the recording of a GDM diagnosis, which is absolutely vital for the audit.

To do this use SNOMED code 11687002 (Gestational diabetes mellitus (disorder)) and put it in the MSD106 Diagnosis (Pregnancy) table.

Also required but not well recorded are:

• BMI
• smoking status
• mode of labour onset
• birthweight of baby
• gestational age at birth

Maternity services must ensure that these data items are recorded in MSDS.

You can contact the GDM audit team at [email protected].