Objective: To estimate gestational diabetes mellitus (GDM) prevalence and hyperglycemia in a large multi-ethnic population and evaluate the differences in glucose measures by age and ethnicity.
Participants and setting: All singleton births in Kaiser Permanente Hawaii (KPH) during 1995-2003.
Measurements: Ethnicity classifications from birth certificate data were linked to KPH's electronic medical records that included laboratory-screening results. GDM screening was performed using the 50-g, 1-hour oral glucose challenge test (CCT) and the 100-g, 3-hour oral glucose tolerance test (OCTT). GDM was ascertained by both the National Diabetes Data Group (NDDG) and the Carpenter and Coustan (C&C) thresholds.
Results: 21,130 (96%) of all pregnant women were screened for GDM using the 1-hour GCT: 21% had glucose levels exceeding the threshold of 140 mg/dL, with the highest rates in Filipinos and Chinese. African American and Caucasian groups had the lowest elevated glucose. Of those with elevated glucose, 1.3% had levels >200 mg/dL, were considered to have GDM, and not tested further; 88% underwent the 3-hour OGTT. Age-adjusted GDM prevalence was 4.4% (NDDG) and 6.6% (C&C). Koreans (6.2%) and Filipinos (6.1%) had the highest age-adjusted NDDGC GDM. African Americans (1.5%), Caucasians (2.5%), and Vietnamese (2.8%) had the lowest.
Conclusions: This is the first population-based study to report GDM prevalence in a large group of ethnicities represented in Hawaii. We found very diverse rates of GDM prevalence and elevated glucose among these groups. These findings point to the need for further research along several avenues, such as maternal-child outcome differences and perhaps ethnic-specific guidelines for GDM diagnosis.