Trends in the Prevalence of Pre-Existing Diabetes and Gestational Diabetes Mellitus among a Racially/Ethnically Diverse Population of Pregnant Women, 1999-2005

Abstract

Objective: To assess changes in prevalence of pre-existing diabetes (diabetes antedating pregnancy) and gestational diabetes mellitus (GDM) from 1999 through 2005.

Research Design and Methods: In this retrospective study of 175,249 women ages 13-58 years with 209,287 singleton deliveries of ≥ 20 weeks gestation from 1999 through 2005 in all Kaiser Permanente hospitals in southern California, information from clinical databases and birth certificates were used to estimate the prevalence of pre-existing diabetes and GDM.

Results: Pre-existing diabetes mellitus was identified in 2,784 (1.3%) of all pregnancies, rising from an age and race/ethnicity adjusted prevalence of 0.81/100 in 1999 to 1.82/100 in 2005 (p for trend < 0.001). Significant increases were observed in all age groups and all racial/ethnic groups. After excluding women with pre-existing diabetes, GDM was identified in 15,121 (7.6%) of 199,298 screened pregnancies. The age and race/ethnicity-adjusted GDM prevalence remained constant from 7.5/100 in 1999 to 7.4/100 in 2005 (p for trend = .07). Among all deliveries to women with either form of diabetes, 10% were due to pre-existing diabetes in 1999, rising to 21% in 2005, with GDM accounting for the remainder.

Conclusions: The stable prevalence of GDM and increase in the prevalence of pre-existing diabetes were independent of changes in the age and race/ethnicity of the population. The increase in pre-existing diabetes, particularly among younger women early in their reproductive years, is of concern.