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 pre-existing diabetes.
“Gestational diabetes mellitus [GDM] appears to have declined about 15% within our study period but … we saw a doubling of pre-existing diabetes in the study,” Jean M. Lawrence, Sc.D., said at the annual scientific sessions of the American Diabetes Association. “We don't know whether this is an increase in the prevalence of diabetes or an increase in screening and diagnosis of previously undiagnosed diabetes. Overall, we saw little change in the proportion of pregnancies with the mother and fetus exposed to diabetes during the pregnancy.”
Dr. Lawrence, an epidemiologist in the department of research and evaluation at Kaiser Permanente Southern California, Pasadena, 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 pre-existing, 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 pre-existing 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 adjustment for maternal age and race/ethnicity, GDM declined during the study period at an average annual rate of 4%, whereas pre-existing diabetes increased by an average of 15% annually.