Study Shows Decline in GDM, Rise in Preexisting Diabetes


CHICAGO – A review of births at a large health maintenance organization suggests the incidence of gestational diabetes is declining, but it is being offset by an increase in preexisting diabetes.

“There is some good news that gestational diabetes mellitus [GDM] appears to have declined about 15% within our study period,” Jean M. Lawrence, Sc.D., said at the annual scientific sessions of the American Diabetes Association. “But the bad news is that we saw a doubling of preexisting diabetes in the study.”

“We don't know whether this is an increase in the prevalence of diabetes or an increasing in screening and diagnosis of previously undiagnosed diabetes,” said Dr. Lawrence, an epidemiologist in the department of research and evaluation at Kaiser Permanente Southern California, Pasadena. “Overall, though, we saw little change in the proportion of pregnancies with the mother and fetus exposed to diabetes during the pregnancy.”

In her study, Dr. Lawrence and colleagues looked at all of the births at 11 Kaiser Permanente hospitals in Southern California from 1999 to 2005, with a total of 209,532 deliveries of infants who were at 20 weeks' gestation or later.

Overall, 8% of the births were to mothers with diabetes, either gestational or preexisting, in each of the years reviewed, with a peak of almost 9% in 2000, and a slight decline totaling less than 1% since then.

The annual prevalence of GDM also peaked in 2000, at the rate of 7.01 cases per 100 women delivered. After that it declined steadily, to a rate of 6.32 cases per 100 women delivered in 2005.

At the same time, the annual prevalence of preexisting diabetes increased steadily from a rate of 1.08 cases per 100 in 1999 to a rate of 2.80 per 100 in 2005.

After adjusting for maternal age and race/ethnicity, the investigators found that GDM declined during the study period at an average annual rate of 4%, whereas preexisting diabetes increased by an average of 15% annually, Dr. Lawrence said.

Both types of diabetes were more common in women of other races than they were in non-Hispanic white women.

Asian women had the highest annual prevalence of GDM, with about double the prevalence of white women.

Black women had the highest annual prevalence of preexisting diabetes, with a 43% higher prevalence than white women.

“We saw changes in all the groups,” Dr. Lawrence said.


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