‘Milestone’ update to diabetes guidelines

A new consensus for diagnosing gestational diabetes mellitus (GDM) has been reached with the release of new Australian guidelines.
 
Updated recommendations described as a ‘significant milestone in maternal health’ were published this week in the Medical Journal of Australia, with screening affecting around 280,000 pregnant women each year.
 
The recommendations from the Australasian Diabetes in Pregnancy Society (ADIPS) raise the blood glucose thresholds for GDM diagnosis and advise more tailored screening for women with known risk factors early in pregnancy.
 
They are recognised as an accepted clinical resource by the RACGP.
 
The rates of recorded GDM have risen significantly over the past 15 years from 6.1% in 2011–12 to 19.3% in 2021–22 according to the Australian Institute of Health and Welfare.
 
That rise accelerated following new diagnostic criteria put in place in 2014 when the guidelines were last updated – introduced despite objections from the RACGP, which said there was a lack of evidence the new thresholds would benefit the extra patients diagnosed.
 
Dr Gary Deed, Chair of RACGP Specific Interests Diabetes, said the RACGP has been calling for a review of the previous guidelines and welcomed the update.
 
‘Evidence changes, and we need to adapt to these issues noting outcomes for women with GDM,’ he told newsGP. 
 
‘It means that potentially we may have had over-diagnosis, but we needed this new evidence to push consensus opinion to accept what we at the RACGP had been calling for.
 
‘The previous decision on diagnostic criteria was also consensus-based but we felt the evidence for those levels were not enough to justify the change that was decided at that time, noting also there was limited RACGP consultation back then.’
 
The threshold for diagnosis is measured using a 75g oral glucose tolerance test (OGTT) at 24–28 weeks’ gestation following fasting, with an initial blood glucose level test followed by further tests after one hour, then two hours.
 
Irrespective of gestation, the guidelines say GDM should now be diagnosed using one or more of the following criteria during a 75 g two-hour OGTT: fasting plasma glucose ≥ 5.3–6.9 mmol/L, one-hour plasma glucose ≥ 10.6 mmol/L, two-hour plasma glucose 9.0–11.0 mmol/L.
 
All women who have not had diabetes detected already are still advised to undergo the OGTT at 24–28 weeks’ gestation under the new guidelines.
 
A study published by the American College of Obstetricians and Gynaecologists in 2020, did not identify any benefits for women or infants screened in Queensland using the criteria adopted in 2014. 
 
‘Except for a very small decrease in respiratory distress, changing the diagnostic criteria has resulted in more GDM diagnoses with no observed changes to measured perinatal outcomes for women with and without diagnosed GDM,’ the analysis concluded.
 
According to ADIPS, the 2025 changes will help ensure ‘appropriate care without over-medicalising pregnancies where the risk of complications is low’.
 
Other peak bodies including Diabetes Australia, the Australian Diabetes Society and the Australian Diabetes Educators Association also expressed their support for the changes in a joint statement welcoming the new guidelines.
 
‘For the first time, Australia’s leading experts in GDM including GPs, obstetricians, midwives, diabetes clinicians and pathologists, have united behind a national approach to improve the consistency and clarity of GDM diagnosis,’ they said.  
 
‘This collaboration marks a significant milestone in maternal health and diabetes care.’
 
Dr Ka-Kiu Cheung, Chair of RACGP Specific Interests Antenatal and Postnatal Care, believes the changes are ‘sensible’, particularly around the early GDM screening for women who are at higher risk.
 
‘The logistics of completing a two-hour OGTT in the first trimester, when many women are still grappling with morning sickness, was always a challenge,’ she told newsGP.
 
‘Although, some women with an equivocal HbA1C may still require the two-hour test.’
 
The guidelines highlight that GDM diagnosis ‘may substantially affect women’s psychological wellbeing’.
 
‘For some women, the diagnosis is a catalyst for positive behavioural change and improved quality of life,’ they state.
 
‘For others, the experience of both internalised stigma (guilt, shame, fear and anxiety) and externalised stigma (labelling, discrimination, depersonalising and judgment), coupled with burden of care that may include financial strain, increased surveillance, and dietary restriction, can lead to a reduced quality of life and negative pregnancy experiences that can persist post partum.’
 
Dr Cheung said the new guidelines ‘represent a practical balance between the experience of consumers/women and research trying to optimise outcomes’.   
 
According to ADIPS, gestational diabetes now affects almost one in five pregnancies.
 
Previously newsGP reported the different approaches could be traced to large trials between 2005 and 2010, which showed an association between hyperglycaemia and adverse pregnancy outcomes and that these outcomes improved with GDM treatment.
 
However, one expert said the GDM threshold had not been clearly defined in 2014, and described the definition chosen by the International Association of the Diabetes and Pregnancy Study Groups as ‘arbitrary’.
 
'Management of type 2 diabetes: A handbook for general practice’ is available on the RACGP website and will be updated in the coming weeks.
 
Log in below to join the conversation.

diabetes gestational diabetes MJA