OBJECTIVES: The aim of this study was to examine the geographic, age, gender and racial variations in the prevalence of diabetes in the U.S. Medicaid population.  METHODS: This retrospective study analyzed a patient sample from the Medicaid fee-for-service (FFS) population in 2008 and 2009. Patients diagnosed with diabetes were identified using International Classification of Disease, 9^thRevision, Clinical Modification (ICD-9-CM) diagnosis codes 250.x0 and 250.x2. Continuous Medicaid FFS enrollment was required during the 2-year study period. Patients were excluded if they had managed care enrollment in any month during the study period. Diabetes prevalence was analyzed by region, state, age, gender and race. The number and percentages of patients in each category were provided in the descriptive analysis. RESULTS: A total of 817,596 patients (16.66%) were diagnosed with diabetes among the Medicaid FFS population in 2008 through 2009. Patients over age 60 years had a higher prevalence (23.00%) than those age 40-59 (19.53%) or 0-39 years (3.27%). Prevalence was also examined by race, with the highest prevalence found in Asian patients (22.17%), followed by Black (20.42%), Hispanic (16.89%), White (15.91%) and Native American (8.89%) patients. Prevalence of diabetes was much higher for female (18.36%) than for male patients (13.99%). U.S. states with the highest prevalence were Maryland (27.42%), Connecticut (26.73%), North Carolina (25.72%), Ohio (23.99%) and Indiana (23.51%). Prevalence trends were also stratified by U.S. region: Midwest (18.12%), South (17.11%), Northeast (16.59%) and West (7.60%).   CONCLUSIONS: The study results illustrate that elderly patients had a higher probability of being diagnosed with diabetes. Asian patients were more likely to be diagnosed with diabetes compared to other races. Female patients were at a higher risk for diabetes.  Patients who resided in the Midwest U.S. region also had an increased likelihood of a diabetes diagnosis.