Obstetrics and Gynecology: One third of pregnant women are not screened for gestational diabetes

Nearly one third of pregnant women are not being screened by a simple laboratory test for gestational diabetes mellitus (gestational diabetes), according to a study of more than 900,000 American women published online today in Obstetrics and Gynecology.  The study, conducted by scientists at Quest Diagnostics, suggests that a large number of women are not being screened according to medical guidelines and may unknowingly put themselves and their babies at risk for complications from gestational diabetes.

The study, titled "Gaps in Diabetes Screening During Pregnancy and Postpartum," also found that only about one in five women who developed gestational diabetes while pregnant were screened for diabetes within six months of completing their pregnancy. Medical guidelines recommend women with gestational diabetes be screened for diabetes between weeks six and 12 postpartum. An estimated 40 to 60 percent of women with gestational diabetes will develop type 2 diabetes within ten years.(i)

"Regardless of ethnicity, weight or age, many pregnant women are not being screened according to guidelines for gestational diabetes, a condition that can cause adverse health effects for mother and child," said study investigator Jon M. Nakamoto, M.D., Ph.D., medical director, Quest Diagnostics.

"We were particularly alarmed to find that women who develop the condition while pregnant are not being screened for diabetes postpartum, despite overwhelming evidence that they are at great risk for developing diabetes later in life," said Dr. Nakamoto. "Considering the diabetes public health crisis, the failure to test these women after their pregnancy is a major concern."

The study assessed de-identified test results of 924,873 women identified as pregnant between the ages of 25 and 40 who were tested by a Quest Diagnostics laboratory. It is the first published study on screening rates for gestational diabetes and postpartum diabetes on a national population that is not limited to data from a single region, hospital or insurance network.

Other key findings:

Many women at risk for gestational diabetes: The investigators found that in the study population, 4.9 percent of women screened between the ages of 18 and 40 – or about 41,000 women nationally – had gestational diabetes.

Number of women with gestational diabetes would nearly double under new screening guidelines: The study also suggests that the number of women with gestational diabetes would have nearly doubled under the new International Association of Diabetes and Pregnancy Study Groups criteria for screening using a 75-g oral glucose tolerance test.  The criteria are based in part on results of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) trial, which studied associations between maternal responses to glucose tolerance testing and adverse health outcomes for mothers and infants.

Obese women have highest risk for gestational diabetes, but are least likely to be screened: Women weighing more than 275 lbs during their pregnancy were 12 percent less likely to be screened, but 348 percent more likely to have gestational diabetes than those weighing between 100-124 lbs. Women with a maternal weight of 250-274 lbs were 6 percent less likely to be screened, but 300 percent more likely to have gestational diabetes than women in the low weight group. According to the American College of Obstetrics and Gynecology (ACOG) and the American Diabetes Association (ADA), weight is one factor in a woman's risk for gestational diabetes.

Ethnicity is stronger predictor of gestational diabetes than maternal weight: The positivity rate for gestational diabetes in Asian American women was 8.7 percent compared to 4.1 percent for African American women. Maternal weight was about 137 lbs on average in Asian women compared to 175 lbs for African American women. Hispanic American women had a positivity rate of about 5.4 percent and an average maternal weight of 156 lbs. Caucasian American women had a positivity rate of 4.2 percent, with an average maternal weight of about 163 lbs. 

"Our study underscores that many factors influence a woman's risk for gestational diabetes. It is important for women and physicians to understand the risks specific to each pregnancy in order to assess the potential value of clinically appropriate screening," said study investigator Harvey W. Kaufman, M.D., senior medical director, Quest Diagnostics. "With diabetes at epidemic proportions, the need for patients to empower themselves through improved knowledge of their individual risks for this disease has never been more compelling."

Gestational diabetes mellitus is diabetes that occurs during pregnancy. It occurs in 4% to 12% of pregnancies. Untreated gestational diabetes increases the risk of pre-eclampsia, premature birth, delivery problems requiring cesarean section, and neonatal hypoglycemia. Gestational diabetes can be treated by controlling glucose with diet, exercise or insulin treatment. Guideline-recommended testing during and after pregnancy involves oral glucose tolerance and blood tests, which are widely available through U.S. laboratories.