To evaluate temporal trends in racial/ethnic groups in rates of serious hypoglycemia among higher risk patients dually enrolled in Veterans Health Administration and Medicare fee-for-service and assess the relationship(s) between hypoglycemia rates, insulin/secretagogues and comorbid conditions.Retrospective observational serial cross-sectional design. Patients were ≥65 years receiving insulin and/or secretagogues. The primary outcome was the annual (period prevalence) rates (2004-2015), per 1000 patient years, of serious hypoglycemic events, defined as hypoglycemic-related emergency department visits or hospitalizations.Subjects were 77-83% White, 7-10% Black, 4-5% Hispanic, <2% women; 38-58% were ≥75 years old; 72-75% had ≥1 comorbidity. In 2004-2015, rates declined from 63.2 to 33.6(-46.9%) in Blacks; 29.7 to 20.3 (-31.6%) in Whites; and 41.8 to 29.6 (-29.3%) in Hispanics. The Black-White rate differences narrowed regardless of insulin use, hemoglobin A1c level, and frequency and various combinations of comorbid conditions. Among insulin users, the Black-White contrast decreased from 34.7 (98.5 vs. 63.8) in 2004 to 13.2 (43.6 vs. 30.4) in 2015; in non-insulin users, the contrast was 25.7 (44.1 vs. 18.4) in 2004 and 10.1 (18.9 vs. 8.8) in 2015.Marked declines in serious hypoglycemia events occurred across race, medications, and comorbidities, suggesting significant changes in clinical practice.