Why does gestational diabetes lead to type 2 diabetes?

For decades, scientists have been baffled as to why gestational diabetes often leads to type 2 diabetes. Now, research led by Deakin University has shown that the answer could be in our genes’ ability to change their behaviour due to signals from the environment.

Women who experience gestational diabetes are seven times more likely to contract type 2 diabetes than women with normal blood glucose levels in pregnancy. Additionally, there is increasing evidence that lifestyle factors including diet and exercise influence the progression of gestational to type 2 diabetes.

Scientists are now beginning to understand how environmental factors can lead to changes to important proteins, called histones, within our cells, and regulate the way genes behave. Changes in gene behaviour caused by the environment, known as epigenetics, mean that factors like poor lifestyle can cause humans to develop diseases.

The researchers sought to measure epigenetic markers across pregnancy and early postpartum and identify markers that could be used as predictors for conversion from GDM to type 2 diabetes. During the two-year study, published in the Journal of Clinical Endocrinology and Metabolism, researchers measured changes in histone proteins in four groups of diabetic and non-diabetic women, during pregnancy and in early postpartum.

The study found that women who develop type 2 diabetes after having gestational diabetes during pregnancy have different modifications of histone proteins from women who don’t go on to experience type 2 diabetes. According to lead researcher Professor Leigh Ackland, this means doctors may be able to predict which women with gestational diabetes would go on to develop type 2 diabetes.

“By understanding the behaviour of specific genes, caused by epigenetic changes, medical practitioners may be able to target lifestyle prevention measures in women with gestational diabetes, so that they don’t go on to experience type 2 diabetes,” Professor Ackland said.

“Women with gestational diabetes who have a high risk of developing types 2 diabetes could be identified and put on a lifestyle modification program.”

Having only followed women up until 20 weeks postpartum, the researchers now want to complete a longer study, as type 2 diabetes can take many years to develop. They have applied for National Health and Medical Research Council funding to continue the study for five years.