Diabetes is increasingly prevalent among women of reproductive age, yet little is known about quality of diabetes care for this population at increased risk of diabetes complications and poor maternal and infant health outcomes. Previous studies have identified racial/ethnic disparities in diabetes care, but patterns among women of reproductive age have not been examined. This retrospective cohort study analyzed 2016 data from Kaiser Permanente Northern California, a large integrated delivery system. Outcomes were quality of diabetes care measures-glycemic testing, glycemic control, and medication adherence-among women ages 18 to 44 with type 1 or type 2 diabetes (N = 9,923). Poisson regression was used to estimate the association between patient race/ethnicity and each outcome, adjusting for other patient characteristics and health care use. In this cohort, 83% of participants had type 2 diabetes; 31% and 36% of women with type 2 and type 1 diabetes, respectively, had poor glycemic control (hemoglobin A1c of ≥9%), and approximately one-third of women with type 2 diabetes exhibited nonadherence to diabetes medications. Compared with non-Hispanic White women with type 2 diabetes, non-Hispanic Black women (adjusted risk ratio, 1.2; 95% confidence interval, 1.1-1.3) and Hispanic women (adjusted risk ratio, 1.2; 95% confidence interval, 1.1-1.3) were more likely to have poor control. Findings among women with type 1 diabetes were similar. Our findings indicate opportunities to decrease disparities and improve quality of diabetes care for reproductive-aged women. Elucidating the contributing factors to poor glycemic control and medication adherence in this population, particularly among Black, Hispanic, and Asian women, should be a high research and practice priority.