Which Pregnant Obese Women Will Get Diabetes? Most Do Not

Though all obese women are treated as though they are at high risk of getting diabetes during pregnancy, that's not true. Only a quarter of them do. A UK team has figured out how to assess risk.

Women who are obese and become pregnant are generally thought to be at high risk of developing gestational diabetes (GD) but in fact, that does not happen to most of these patients.

A team in the UK has come up with a way to predict which of these mothers-to-be are at highest risk.

They studied 1,303 obese pregnant women of whom 337 did develop GD. Then they tried to determine what test results or traits might have predicted high risk and identified the 15% to 30% of pregnant obese patients who would become diabetic. (The variation is due to different standards for measuring the onset of diabetes.)

“There is currently no accepted strategy to identify obese women at high risk of gestational diabetes, early in pregnancy,” lead author Sara White of King’s College London said.

That would be an important tool, she said, “”Correctly identifying obese women with heightened risk of GD early in pregnancy would enable targeted intervention in women most likely to benefit.”

The condition also causes problems for these women’s newborns, including fetal macrosomia, unusually large size.

In their retrospective study, White and colleagues looked at the medical records of patients in a study called UPBEAT, a multi-center randomized controlled study of interventions that were hoped would stop at-risk pregnant women from developing GD, including pharmacological intervention, diet changes, and exercise. (None worked very well.)

They looked at oral glucose tolerance test results, from 23 weeks to 32 weeks gestation. The researchers also looked a clinical and demographic variables, ranging from age, ethnicity,

socioeconomic status and family health histories. They also took skinfold measures of patients to chart where they carried their extra weight, such as around the waist or on their hips.

Having a BMI of 30 or greater is a poor predictor of risk, they found, “With escalating rates of obesity worldwide, these models will become increasingly un-useful,” they wrote.

Candidate biomarkers included insulin resistance, adipokines, inflammatory, and endothelial markers such as interleukin-6 or high sensitivity C-reactive protein and tissue plasminogen activator antigen. They also measured liver markers, and lipid measurements. (A full list is in their study as linked at the end of this article.)

They were able to pinpoint four clinical characteristics and six candidate biomarkers with the best predictive values.

Women who developed GD were older than those who did not, more likely to have had GD in a previous pregnancy or to have a first-degree relative with type 2 diabetes. They also had higher BMI and blood pressure. Ethnicity was not shown to be a factor.

Those who became diabetic also had more fat around the neck, waist, hip, wrist, and mid-arm than those who did not—regardless of BMI.

Lab tests showed that the women who developed GD also had higher measures of lipoprotein particles subclasses, some fatty acids, amino acids, and ketone bodies.

While these traits and test results are far from a one-size-fits-all test, they can be done at low cost and applied in settings outside of fully equipped hospitals or clinics, she wrote.

“One of our models focused on a few clinical factors and biomarkers already readily available in clinical practice and which incurred minimal cost,” she wrote, and in addition they have identified a model that “does not require blood sampling [and] could be developed for low and middle income countries where the prevalence of gestational diabetes and obesity is rapidly increasing.”

The full text of the study “Early Antenatal Prediction of Gestational Diabetes in Obese Women: Development of Prediction Tools for Targeted Intervention” was published December 8 in PLOS one.

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