Relationship Now Doubted : Study Sheds New Light on Diabetes-Pregnancy Link

Gestational diabetes--a form of diabetes diagnosed during pregnancy--may not be caused by pregnancy as previously believed, according to study results released Thursday by the National Institute of Diabetes and Digestive and Kidney Diseases.

The condition more likely may be a precursor for the development of adult diabetes in some women, regardless of whether they become pregnant, the institute said.

Gestational diabetes, diagnosed in up to 5% of pregnant women in this country, may in fact precede pregnancy and be detected during the routine testing that accompanies prenatal care, the report said.

The disease increases the risk that the newborn will have health problems and that the mother will develop diabetes in the future. It is similar to, but milder than adult, or noninsulin-dependent diabetes.

Higher Diabetes Rate

About 25% of women with gestational diabetes develop adult diabetes, while less than 2% of women who have not had gestational diabetes will develop diabetes later, the institute said.

“The message of the study has more to do with emerging diabetes than it does with pregnancy,” Dr. Maureen Harris, author of the report, said in an interview. “This designates a group of women at higher risk for developing diabetes--whether or not they get pregnant.”

In the study, published in the May issue of the journal “Diabetes Care,” researchers tested the blood of 817 nonpregnant women of child-bearing age and found that just as many of them tested positive for the disease as would be expected among the same number of pregnant women.

Moreover, the women in the study who tested positive had the same risk factors for diabetes as pregnant women with gestational diabetes. The risk factors are obesity, having a family history of diabetes and being 25 or older, the researchers said.

Control Group’s Rate

In the study group, 3.8% of the nonpregnant women had blood glucose levels that met the standard diagnostic criteria for gestational diabetes, the report said.

“Gestational diabetes may not be associated with or caused by pregnancy,” said Harris, director of the institute’s National Diabetes Data Group. “It simply may be a form of glucose intolerance that is not severe enough to be called diabetes that is already present in these women--and only gets detected in this prenatal testing that women go through when they become pregnant.”

Women who suffer from adult diabetes are more likely than others to bear children with congenital defects, Harris said, but she added that she does not believe women with gestational diabetes necessarily run the same risk.

“The risks associated with gestational diabetes are transient,” she said. “They include hypoglycemia (low blood sugar), respiratory distress and big birth weight, which can carry some problems for the baby.”

Seventh Killer Disease

Diabetes, which afflicts an estimated 11 million Americans, impairs the body’s ability to use the products of digested food for energy. The diabetic body cannot use glucose--a form of sugar that is its primary fuel--for energy, and glucose builds up in the blood. The long-term complications of diabetes make it the seventh most common cause of death in the nation, according to the institute.

“For physicians concerned with the health of the fetus and the future health of the mother, and for scientists concerned about understanding how diabetes develops, it is essential to know when gestational diabetes begins,” Harris said. “Without this knowledge, the term ‘gestational diabetes’ appears to be inappropriate and misleading.”