Diabetes is difficult to study. Once it is diagnosed, the chances of elucidating the causes are limited. Because about 3% of pregnant women in Denmark develop gestational diabetes, Danish researchers now monitor women with previous gestational diabetes and then follow how the disease develops. The initial studies show that women with previous gestational diabetes have a high incidence of nonalcoholic fatty liver disease (NAFLD).
Many women develop gestational diabetes during pregnancy, and the diabetes disappears again for most of them after they give birth. However, research shows that this group of women should definitely not use this normalization as a cushion. Evidence has demonstrated that the incidence of type 2 diabetes among these women is much higher than among others. A major Danish research study is underway to monitor the progression from no diabetes to the development of type 2 diabetes.
“For several years, we have known that, for the sake of the child, we should pay special attention to women with poorly regulated blood glucose during pregnancy. Research also shows that we should also keep an eye on the women because up to 70% develop type 2 diabetes later in life. In addition, our new study shows that they are not only at risk of developing type 2 diabetes but also non-alcoholic fatty liver disease,” explains Tina Vilsbøll, Head of Clinic and Professor, Steno Diabetes Center Copenhagen.
This Danish research project is monitoring 100 women for 5 years about 5–10 years after a pregnancy with gestational diabetes. The researchers will monitor how the regulation of blood glucose and insulin resistance develop after pregnancy.
“After pregnancy ended, all had normalized their metabolism, but when we included these women in our study 5–10 years after their pregnancy, many had abnormal glucose tolerance at the start of the study and a noticeable proportion had elevated liver fat. In the long term, we expect several of them to develop type 2 diabetes.”
The study is monitoring women every 6 months for 5 years and is thereby uniquely able to monitor the development of type 2 diabetes. Because the study is underway, it is too early for the researchers to draw firm conclusions on the women’s long-term prognoses. However, the researchers can already see indicators through ultrasound scanning that are troubling for many of the women.
“Almost one quarter of the women already have clear signs of non-alcoholic fatty liver disease at the beginning of the study. The accumulation of fat in the liver can result in the liver cells swelling up in severe cases and, in a worst-case scenario, this can have significant consequences. It is therefore worrying that these rather young women already display clear signs of non-alcoholic fatty liver disease so early in their lives.”
The “dream study”
Although non-alcoholic fatty liver disease is relatively common, affecting 20–25% of the population in high-income countries, it is much more common among people with type 2 diabetes: 43–70%. The researchers will therefore also examine the direct link between these two diseases more closely.
“Although the link between these two diseases is clear and well documented, we do not sufficiently understand the pathophysiology. We hope that the study will provide some answers. Which of the two comes first, and are the two diseases directly connected? What metabolic changes take place first among the women at high risk? These are some of the answers we hope to find by monitoring these women in the long term.”
For the same reason, Tina Vilsbøll also characterizes the study as somewhat of a dream study. The major challenge diabetes researchers often face is being able to monitor the development of the disease at the early stages when the regulation of blood glucose begins to go wrong.
We can already see that this group of pregnant women will help provide important information on how diabetes develops and especially how to prevent this from happening. Some of the women will therefore also receive preventive treatment to determine whether we can influence the development of some of these metabolic changes.
“Nonalcoholic fatty liver disease is prevalent in women with prior gestational diabetes mellitus and independently associated with insulin resistance and waist circumference” has been published in Diabetes Care. The Novo Nordisk Foundation awarded grants to Tina Vilsbøll, a main author, in 2015, 2016 and 2017.