Gestational diabetes rates have skyrocketed in Melbourne’s southeast within a short timeframe, putting more Victorian mothers and babies at risk of complications and piling additional pressure on the state’s health system.
A team of researchers from Monash University analysed data relating to more than 1.7 million women who gave birth between 2016 and 2021 for gestational diabetes, a condition that affects almost one in five pregnant women, in which blood sugar level is elevated during pregnancy.
Researchers found consistently higher risk of the condition around suburbs like Werribee and Craigieburn, in Melbourne’s west and north.
In these hotspots, gestational diabetes can affect more than one in five women.
However, the data showed a new hotspot had become firmly established by 2020-21, centred on suburbs like Glen Waverley, Wantirna South, Mulgrave, Dandenong and Cranbourne.
In contrast, most of Melbourne’s inner suburbs and the wealthy bayside areas consistently reported lower-than-average rates of gestational diabetes across the six years of data.
Interestingly, leafy Olinda, Monbulk and Emerald went from being “cold spots” for gestational diabetes in 2016 to in line with the Australian average by 2021.
It was already known gestational diabetes had been on the rise, its incidence more than doubling in Australia between 2013 and 2022. However, this study – published in the scientific journal BMJ Open – is the first to map pockets of Australia where the condition is disproportionately distributed.
In her first media interview about the research, Monash University Professor Jacqueline Boyle said it was important to track gestational diabetes rates over time because the condition could increase pregnancy risks like pre-eclampsia (high blood pressure), macrosomia (an exceedingly high birth weight, often over 4kg or 4.5kg), and caesarean delivery.
“Women with gestational diabetes also have an increased risk of developing type 2 diabetes, cardiovascular diseases, and gestational diabetes in the subsequent pregnancy,” Boyle said.
PhD student Wubet Worku Takele, who authored the paper under the guidance of Boyle and others, said there were likely many socio-environmental factors contributing to the hotspots.
“In most cases, clustering of gestational diabetes overlaps with areas of socioeconomic disadvantage and areas with high [concentration] of non-European migrant women, known to have an increased risk of diabetes in relation to genetic, cultural and structural factors.”
He added that other environmental factors – like limited access to healthy food outlets and elevated air pollution – may also increase risk.
“Other reasons may relate to a lack of culturally responsive health promotion resources and health services for diverse populations.”
The study relied on Statistical Areas Level 2 (SA2) data, which often – but not always – correlates to a suburb-by-suburb breakdown. The incidence of gestational diabetes per SA2 was age-standardised.
Hot and cold spots were divided into significant and non-significant zones. ‘Significant’ hot or cold spots had a confidence level of more than or equal to 95 per cent, while insignificant zones had a lower confidence level of 90 per cent.
Who is at greater risk of gestational diabetes?
- Women who’ve been diagnosed with gestational diabetes previously
- Pregnant women aged 40 or older
- Women with a higher BMI
- Those with a family history of type 2 diabetes
- First Nations women, as well as women from African, Melanesian, Polynesian, South Asian, Chinese, Southeast Asian, Middle Eastern, Hispanic and South American backgrounds.
The emerging gestational diabetes hot spots, in suburbs like Dandenong and Springvale, popped up before the diagnostic criteria were narrowed in Victoria. But these suburbs remain areas of concern, according to doctors.
Alison Nankervis, a senior physician for the diabetes service at the Royal Women’s Hospital – who did not work on this study – said the maps were useful because even well-resourced hospitals were “buckling” under the numbers of women being diagnosed.
Nankervis said that the diagnostic criteria for gestational diabetes was tightened late last year after a “fraught debate” about whether too many women were presenting with the condition and whether health services could manage.
A study published in May 2023 found that a third of participants diagnosed with early gestational diabetes via World Health Organisation Criteria did not have the condition after taking a repeat oral glucose tolerance test at 24-28 weeks’ gestation.
Nankervis said the Royal Women’s saw an initial dip in patients with the condition following the change, but that now there’s “just as many women with gestational diabetes with the new criteria as the old”.
“It’s a big group of women we have to manage as effectively as we can. Footscray and the Northern hospitals, they’re really under the pump and not as well-resourced as we are. And in the southeast – areas like Dandenong – they are very pressured and need more resourcing.”
The good news, Nankervis said, was that gestational diabetes could be effectively managed with lifestyle changes and medication.
“I’d encourage women not to see it as a failure or guilt-trip. It’s very treatable.”
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Broede Carmody is a health reporter for The Age. Previously, he was a state political reporter for The Age and the national news blogger for The Age and The Sydney Morning Herald.Connect via X or email.