Scientists may be one step closer to being able to detect gestational diabetes mellitus (GDM) earlier in pregnancy. The move may be able to prevent irreversible complications and/or improve treatment for the common pregnancy disorder. It could also improve outcomes for mother and child in the long-term, when repercussions of GDM emerge.

Dealing with gestational diabetes

GDM is the most common disorder affecting pregnant women, seen in anywhere from 2% to 10% of pregnancies in the U.S. every year. It can damage the organs in both the fetus and in the mother. During pregnancy, it can cause birth defects, high blood pressure, preeclampsia, babies with large birth weight, preterm birth, or the likelihood of needing a C-section.

As it stands, pregnant people are screened for GDM between 24 and 28 weeks. The glucose challenge test, or one-hour glucose tolerance test, involves drinking a sugary substance and having blood drawn about an hour later. If diagnosed, you need to closely monitor your diet, exercise, and blood sugar. Half of all women with GDM go on to develop type 2 diabetes later in life, the Centers for Disease Control and Prevention reports. They are also at a higher risk for cardiovascular disease.

Related: It's science: The glucose test is safe for pregnant women: But there are alternatives if you want them

Spotting GDM sooner

A team from UCLA pinpointed biomarkers that they believe may be indicators of GDM early in pregnancy. Their study appeared in PLOS ONE.

Researchers collected blood samples from 24 women during each trimester and at delivery. Then they looked at extracellular vesicles (EVs) that are secreted from the placenta (this starts at about 6 weeks into pregnancy). The EVs transport microRNA genes (miRNAs) in the mother’s blood. 

The researchers noticed a unique expression of miRNA in EVs from the first trimester in women who went on to develop GDM. The expression of miRNA differed compared to women who did not have GDM later in pregnancy.

The UCLA team also took blood from three healthy women who were not pregnant for control purposes.

The changes in miRNA suggests the miRNAs had a role in the development of the disease instead of factors secondary to the condition itself (or treatments like insulin, which can impact the miRNA content of circulating EVs).

"As pregnancy complications continue to rise worldwide, there have been increasing efforts to study with urgency the first-trimester as a window of opportunity for early identification and prediction of GDM, and the optimal point to take action to prevent maternal disease," Dr. Sherin Devaskar, lead author of the study and physician-in-chief of UCLA Mattel Children's Hospital, says in a statement.

Related: Gestational diabetes may not be linked to pregnancy weight gain, study says

The findings also imply that the miRNA may be communicating with other maternal organs and cell types, and interacting with signaling pathways involved in metabolism and inflammation. This could impact the maternal metabolic adaptations that have been seen in women with GDM, the researchers say, providing a possible clue as to the higher risk for type 2 diabetes or cardiovascular disease seen down the line.

Devaskar says the findings are “promising” but notes that more research is needed. (After all, it was a relatively small study.)

But the findings provide more evidence that GDM starts earlier in pregnancy than the time when it is routinely diagnosed at the end of the second trimester. 

If women knew earlier on that they have GDM, that knowledge may help them and their healthcare providers better manage the condition. It also may help pregnant women avoid birth complications that are otherwise not reversible—and reduce their risk of chronic disease later in life.

Sources

KC K, Shakya S, Zhang H. Gestational Diabetes Mellitus and Macrosomia: A Literature Review. Ann Nutr Metab 2015;66(suppl 2):14-20. doi: 10.1159/000371628

Thamotharan S, Ghosh S, James-Allan L, Lei MYY, Janzen C, Devaskar SU. Circulating extracellular vesicles exhibit a differential miRNA profile in gestational diabetes mellitus pregnancies. 2022. PLoS ONE 17(5): e0267564. doi:10.1371/journal.pone.0267564