A new peer-reviewed study from Bar-Ilan University has shown that it is possible to study a pregnant woman’s gut microbes to predict as early as the first trimester whether she will later be diagnosed with gestational diabetes mellitus (GDM).
This is a significant finding that could ultimately lead to better prevention and treatment of the serious disease that can lead to complications for mothers, their unborn babies, or both, the scientists said.
The study applied a machine learning model to fecal and saliva samples and medical records of a cohort of 400 Israeli women still in the first three months of their pregnancies. Those who were found to have specific combinations of bacteria, types of fatty acids, and inflammatory markers in their guts had a much higher chance of developing GDM.
“At the time of the writing of the paper, we were successful in 83 percent of the cases in predicting which of the women would develop the condition,” said Prof. Omry Koren of the Azrieli Faculty of Medicine, the lead researcher on the study.
As of today, pregnant women are generally tested for GDM only in their second trimester, at 26 weeks on average. This is the period in pregnancy when insulin resistance increases.
Approximately 10% of pregnant women without a known history of pre-diabetes or diabetes are diagnosed with GDM worldwide. In some cases, diabetes can be managed with a strict diet and exercise, but in others, the injection of insulin is required. Although GDM disappears after the birth of the baby, it leads to a higher risk of the mother developing Type 2 diabetes later on, and of her child to be obese.
“We know that 50% of the patients with GDM will become diabetic within 10 years of their pregnancy,” said Prof. Eyal Sheiner, chairman of the department of obstetrics and gynecology at the Soroka University Medical Center.
Sheiner, who was not involved in the study, remarked that investigating GDM prevention by scrutinizing gut microbiota — rather than blood for elevated sugar levels — is an interesting and worthy approach, and looked forward to seeing where the research will lead.
Rebecca Einstein Schorr told The Times of Israel she was amazed to hear of this scientific advance and sorry that the knowledge was not available when she was pregnant with her three children, who are now 15, 19, and 22. The 52-year-old Emmaus, Pennsylvania resident had GDM in each of her pregnancies.
“In the first pregnancy, especially, it was terrifying… you feel like your body is betraying you. You can’t keep your baby safe. It was very upsetting,” she said.
Her diagnosis came as Passover was near. She became anxious that if she ate too much matzah and other traditional carbohydrate-rich holiday food, she could send her fetus into glucose shock. It took the joy out of the holiday and her anticipation of the remainder of the pregnancy.
Schorr fell into the 10% of women with gestational diabetes for whom diet and exercise are not enough and required insulin.
“So here I was, just a completely regular pregnant person, and boom! Fast forward and I’m checking my blood sugar all the time and having to take insulin throughout the day. That was a huge mental adjustment. Of course, the biggest motivation was to promote gestation, to preserve the baby’s life. But diabetes is a full-time job,” she said.
Koren spoke to The Times of Israel from Valencia, Spain, where he is on a year-long research sabbatical studying the bacteria in mother’s milk. He explained that an additional element of the GDM study published in Gut involved feeding the feces from the first-trimester study subjects into germ-free mice.
“These are mice that we grow under special conditions. They’ve never seen a bacteria in their life,” Koren said.
The mice that received feces from the women who eventually got GDM developed higher glucose levels than the mice who were fed the feces of the women who did not develop the condition.
To test whether this is not a phenomenon limited to Israeli women, Koren and his team collaborated with researchers in the US and Finland. Fecal samples from women in their first trimester from those countries were collected and inserted into the special mice. The results were the same.
“This showed that this is a universal phenomenon,” Koren said.
He reported that there are efforts through Bar-Ilan University to set up a company that would offer products for predicting pregnancy complications, gestational diabetes included. But in the meantime, his best advice to all pregnant women is to adhere to a healthy, low-sugar diet from the beginning, and for medical staff to keep an eye out for insulin resistance signs before the 26th week.
“In Israel, we measure the fasting blood glucose of all pregnant patients. If a woman has a glucose level higher than the threshold, we don’t ignore it,” Sheiner said.
Schorr, who now has Type 2 diabetes, would have very much welcomed a GDM prediction tool when she was expecting her children.
“Early prediction would help psychologically and emotionally because there’s more prep time. When you get diagnosed much later in your pregnancy, you have a lot of information thrown at you that you have to process very quickly and scramble,” she said.