Gestational diabetes soars by 70% in Australia: what’s driving the surge?

Gestational diabetes mellitus (GDM) prevalence has surged by almost 70% in five years, putting thousands of women and their babies at risk of future health complications. Of particular concern is the Northern Territory, which has almost tripled its incidence of GDM, while Victoria has doubled its incidence.

A Monash University meta-analysis was published in the Australian and New Zealand Journal of Public Health using data from over 1.8 million pregnant women compiled from the National Diabetes Services Scheme (NDSS) and Australian Bureau of Statistics (ABS).

Of the 1 845 182 women who gave birth in Australia from 2016 to 2021, the age-standardised incidence of GDM in each state/territory rose from:

• New South Wales: 10.0% to 14.0%
• Victoria: 7.2% to 14.4%
• Queensland: 9.0% to 14.5%
• South Australia: 9.2% to 14.5%
• Western Australia: 6.8% to 11.8%
• Australian Capital Territory: 11.2% to 22.4%
• Northern Territory: 5.3% to 16.8%
• Tasmania: 8.2% to 14.8%
• Nationally: 8.2% to 12.2%

Who’s most at risk? Ethnic and socio-economic disparities

The study authors highlighted several possible risk factors behind the trend “including the increasing prevalence of overweight or obesity among pregnant women, increasing age during pregnancy, and changing migration patterns with a higher proportion of people from ethnic groups at increased risk”.

They specifically looked at the nationality of the mothers, finding: “a significant increase in the incidence of GDM over time was observed in almost all ethnic groups, with the most marked rise in women born in South-East and South and Central Asia. The risk of GDM over time was most marked in women from the most socio-economically disadvantaged groups.”

The incidence of GDM in women from South-East Asia rose from 12.2% to 22.5%. In a subgroup analysis, the highest rise was from women born in Vietnam, followed by those from the Philippines.

For women from South and Central Asia, GDM rates rose from 14.4% to 24% with the highest increase in women born in India and Pakistan.

GDM significantly increased in all ethnic groups, apart from those born in North-west Europe and the Americas. Increases in GDM were less pronounced in Australian-born mothers, rising from 7.2% in 2016 to 9.0% in 2021.

Diabetes Australia Chief Medical Officer Professor David Simmons told InSight+ that these results are concerning but not surprising.

“There’s a whole range of reasons, from genetics to things that happen in childhood and exposure to hyperglycaemia or gestational diabetes for the baby in the womb who then grow up to have an increased risk.

“And then also there are changes in lifestyle with reducing amounts of physical activity and changes in the calorie content of the food,” he explained.

In populations from South and Central Asia, genetic factors, birth weight and body fat distribution impact diabetes risk.

“It’s been known for a long time that South Asian people have smaller babies at birth, and then their growth catches up. That is associated with an increased risk of diabetes and an increased risk of obesity later in life.

“They have a different fat distribution. They put their adipose tissue on their tummies and on their neck. Particularly, fat on your abdomen makes you more insulin resistant,” Professor Simmons said.

People from East and South-East Asia also have increased risk.

“There are some genes that have been identified that are associated with an increased risk of gestational diabetes. And then there are quite a few differences in the effect of food and physical activity in, for example, those who are Chinese.

“If you have a look, globally, most other non-European groups have an increased risk of diabetes but they’re all slightly different,” he said.

According to the study authors, there may also be sociocultural factors contributing to this rise in Australia, as South Asian women may “experience higher expectations to focus primarily on housework and family-related responsibilities, limiting the opportunity to engage in health promotion activities, such as physical activity.”

“For migrant women, inadequate utilisation of reproductive health care services, meaning less opportunity to engage with preventive health practices can lead to increased risks, contributing to adverse pregnancy outcomes, such as GDM,” the authors wrote.

The need for culturally sensitive prevention

The study highlights the need for culturally sensitive diabetes education.

“Implementing tailored prevention strategies that are culturally responsive and addressing core social determinants of health (eg, socio-economic status) may help alleviate the burden of GDM in Australia,” the authors wrote.

According to Professor Simmons, there are many diverse informational materials available through the National Diabetes Services Scheme (NDSS).

“There are informational materials in many languages, videos and also written materials. The materials are quite diverse,” he said.

There are also state-based lifestyle programs such as Get Healthy in Pregnancy in NSW, which provide culturally appropriate dietary and exercise advice from a health coach. They can also link women who have had prior GDM to one of these lifestyle programs.

“Depending on where you are, (you get) six to 10 calls, that help give you guidance on how to do the things that prevent GDM if you get pregnant again,” he explained.

Diagnosing and managing GDM is critical in pregnancy as it reduces the risk of adverse pregnancy and birth outcomes, including preeclampsia, caesarean birth, breathing problems at birth, and preterm birth.

However, as Professor Simmons highlighted, GDM is just one part of a life course condition.

“[Women diagnosed with GDM] are at an increased risk of developing type two diabetes into the future, an increased risk of cardiovascular disease and there’s recently [been] a paper as well on increased risk of chronic kidney disease. So this group of people, we need to identify them,” Professor Simmons concluded.

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