New research studied 3500 Illawarra Shoalhaven women over eight years
A new study has stressed the need for clear guidelines on the early screening, diagnosis and treatment of gestational diabetes mellitus (GDM), to both prevent increased anxiety and stress among women at a delicate time in pregnancy and reduce the burden on clinicians and the health system.
Led by researchers from the University of Wollongong (UOW), working alongside clinicians from the Illawarra Shoalhaven Local Health District (ISLHD), the study of nearly 3,500 pregnant women in the Illawarra and Shoalhaven found that diagnosing and treating GDM in the first trimester didn't improve health outcomes for most mothers and their babies.
However, for those with higher fasting blood sugar levels, there were some benefits, such as a reduced risk of respiratory distress and emergency cesarean sections, if they received treatment immediately, in the first trimester.
The findings were revealed in a peer-reviewed paper released in Diabetes Research and Clinical Practice this month (November 2024), titled 'Early screening and diagnosis of gestational diabetes mellitus (GDM) and its impact on perinatal outcomes'.
GDM is a type of diabetes that is diagnosed in pregnancy and, if not managed properly, can have increased risks for the health of the mother and fetus. It is a common pregnancy complication, with approximately 18 per cent of women aged 15-49 who gave birth in 2021-2022 diagnosed with the condition.
All women are screened for GDM during pregnancy, usually between 24 and 28 weeks. However, some women, particularly those in high-risk groups, are screened early, in the first 12 weeks of pregnancy, via a fasting blood test.
The researchers examined the deidentified data of 3454 women who gave birth in the Illawarra region between 2012 to 2020.
Co-author Dr Monique Francois, from UOW's School of Medical, Indigenous and Health Sciences, said the study's findings were surprising.
"Early screening for GDM has become common but the evidence on whether it actually benefits the woman and baby is conflicting. On one hand, it has been argued that only screening women who have a high risk of developing GDM could miss many other potential cases, but on the other hand, we don't know whether universal early screening will help or even harm women," she said.
The study revealed that a woman's fasting glucose is the greatest indicator of whether a baby will be born large for their gestational age (a medical term that typically refers to babies born in the 90th weight percentile or above).
"Our research found there was no advantage to diagnosing and treating women who had a lower fasting glucose of 5.1-5.2mmol/L, as it did not change the risk of having a baby that was large for its gestational age," Dr Francois said.
"For women who had a fasting glucose of 5.3mmol/Lor higher, there were advantages in early screening and treatment, as long as they received immediate treatment after diagnosis. In this group, we saw 54 per cent fewer emergency caesareans and babies had 50 per cent reduction in respiratory distress.
"An increase in respiratory distress is often a complication of a GDM pregnancy. It also places a greater strain on hospital resources, particularly if babies require neonatal care."
Dr Francois said the shift towards early screening has, in some cases, led to greater anxiety and stress among women with low fasting glucose as well as increased health care burden.
This study highlights the need for further research into more individualised and personalised diagnosis and treatment of GDM and is an important piece timely evidence as currently the Australian Diabetes in Pregnancy Society is reviewing evidence and creating guidelines for early diagnosis of GDM.
Beenu Bastian, co-author of the study, PhD Candidate and Diabetes Educator with ISLHD, said the Illawarra was the perfect area to conduct the research as its demographics are on par with the general Australian population. The region also had very high rates of early screening which is very hard to achieve in many areas.
She said the research reflects the need for greater clarity around diagnostic cut-offs and uniform evidence-based guidelines on the treatment and management of GDM across Australia.
"Our study shows that the level of fasting glucose has a greater impact on whether or not the baby will be large at birth, rather than the weeks of gestation at diagnosis. Women who have a higher fasting glucose are at an increased risk of having a large baby," Ms Bastian said.
"It is important for all health care providers to understand the pros and cons of early screening and the prompt referral of all women with higher fasting glucose for treatment of GDM."
