Newswise — the same complex genes that contribute to an increased risk of type 2 diabetes may also increase the risk of gestational diabetes among women of South Asian descent, a study published today in eLife Offers.
This discovery may lead to new ways to identify women who might benefit from interventions to prevent diabetes during pregnancy.
People of South Asian descent have a higher risk of developing type 2 diabetes. Women in this group are also more likely to develop a condition called gestational diabetes during pregnancy than women of European descent. But why South Asians are at increased risk from these two conditions is currently unclear.
“Only a few studies have looked at how genetic and environmental factors interact in gestational diabetes in South Asian women,” says lead author Amel Lamri, a research associate at McMaster University and the Population Health Research Institute (PHRI) in Ontario, Canada. “No one has looked at how genes associated with type 2 diabetes interact with environmental factors to contribute to gestational diabetes in South Asian women.”
To fill this gap, Lamre and colleagues evaluated the relationship between genes associated with type 2 diabetes, environmental factors, and gestational diabetes. They examined whether the presence of genetic imprinting associated with risk of developing type 2 diabetes was also associated with gestational diabetes in 837 and 4372 South Asian women participating in the SouTh Asian BiRth CohorT (START) study, and the Born in Bradford (BiB) study, respectively.
The team measured the genetic risk of type 2 diabetes using a polygenic risk score, which estimates an individual’s genetic risk of developing a disease based on the number of risk alleles they have. The researchers found that South Asian women with high risk scores for type 2 diabetes were more likely to develop gestational diabetes. Each incremental increase in the score was associated with a 45% increase in the risk of developing the condition.
When the scientists studied the risk of gestational diabetes at the population level, they found that having a polygenic risk score in the upper third explained 12.5% of the risk of developing the condition in South Asian women. When they combined a family history of type 2 diabetes with a polygenic risk score in the upper third, they explained a 25% increased risk of developing gestational diabetes.
“These findings show that a higher risk score for type 2 diabetes and a family history of diabetes are significantly and independently associated with gestational diabetes in women of South Asian descent,” Lamre explains.
The scientists also looked at whether environmental factors modified these genetic risk factors. Most of the environmental factors they considered (with the possible exception of BMI and diet quality) did not significantly change the risk of developing diabetes during pregnancy in both studies. But the authors note that the studies may not have been large enough to detect more modest environmental effects, and that more studies are needed to confirm the modulating effects they observed.
“Our findings support the idea that type 2 diabetes and gestational diabetes share a common genetic background,” concludes lead author Sonia Anand, Michael J. DeGroote Senior Associate in Population Health and senior scientist at PHRI, McMaster University, and Hamilton Health Sciences. “If future studies confirm our findings, this information may help identify women who would benefit most from interventions to help prevent diabetes during pregnancy.”
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