To report the national proportions and trends of adult hospitalizations with diabetes in the United States during 2000-2018.We used the 2000-2018 National Inpatient Sample to identify hospital discharges with any listed and primary diagnoses for diabetes, based on International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) and ICD-10-CM codes. We calculated proportions and trends of adult hospitalizations with diabetes, overall and by subpopulations. We used the Nationwide Readmissions Database to assess calendar-year and 30-day readmission rates.From 2000 to 2018, the proportion of hospitalizations among adults ≥18 years increased from 17.1% to 27.3% (average annual percentage change [AAPC] 2.5%; P 0.001) for any listed diabetes codes and from 1.5% to 2.1% (AAPC 2.2%; P 0.001) for primary diagnosis of diabetes. Men, non-Hispanic Black patients, and those from poorer zip codes had higher proportions of hospitalizations with diabetes codes.In recent years, approximately one-quarter of adult hospitalizations in the United States had a listed diabetes code, increasing about 2.5% per year from 2000 to 2018. These data are important for benchmarking purposes, especially due to disruptions in health care utilization from the COVID-19 pandemic.