Racial and ethnic disparities in diabetes risk after gestational diabetes mellitus

Aims/hypothesis To investigate racial/ethnic disparities in diabetes risk after gestational diabetes mellitus (GDM). Methods This is a retrospective cohort study of women enrolled in the Kaiser Permanente Southern California health plan from 1995 to 2009. GDM status was identified on the basis of plasma glucose levels during pregnancy. The incidence of diabetes after the first delivery complicated by GDM before 31 December 2009 (n=12,998) was compared with the experience for women without GDM (n=64,668) matched on maternal age at delivery, race/ethnicity and year of delivery (1: 5 ratio). Matched Cox regression was used to compare the RRs of diabetes associated with GDM within and across racial/ethnic groups. Results Compared with the women without GDM, the HRs (95% CI) of diabetes for women after GDM were 6.5 (5.2, 8.0) in non-Hispanic white, 7.7 (6.8, 8.7) in Hispanic, 9.9 (7.5, 13.1) in black and 6.3 (5.0, 7.9) in Asian/Pacific Islanders after adjustment for parity, maternal education, comorbidity and number of outpatient visits before the index pregnancy. The HR of diabetes for black women was significantly higher than that for non-Hispanic white women (p=0.032). Further adjustment for prepregnancy BMI reduced the diabetes risk association with GDM for each racial/ethnic group, but did not explain the risk differences across groups. Conclusions/interpretations Racial/ethnic disparities exist in risk of diabetes after GDM. Black women with GDM had the highest risk of developing diabetes. This highlights the importance of developing an effective diabetes screening and prevention programme in women with GDM, particularly black women with GDM.