ABSTRACT Mental illness is associated with increased risk of diabetes and sub-optimal diabetes care. Diabetes care in a sample of Medicaid-eligible adults (ages 18-59) served by the San Bernardino County (California) Department of Behavioral Health during late 2004 was examined. Publicly-funded services provided to 4,071 adults between May 2004 and April 2005 were extracted from the State's paid claims file. Co-morbid diabetes (ICD-9 code 250.xx) was found in 405 (10%) patients. Chi-squared and t-tests revealed that those with diabetes were significantly older (44.5 vs. 38.6 years of age), female (70% vs. 61% of all patients), less likely to be white (44% vs. 52%), and more likely to be diagnosed with schizophrenia (43% vs. 36%). Adherence to American Diabetes Association guidelines for quality of care was examined by searching claims for CPT codes indicating lipid testing, HbA1c testing, and eye examinations. Only 61 patients (15.1% of 405) received all three services during the year, while 57.3% received lipid testing, 51.4% received HbA1c testing, and 32.1% received eye exams. There was no disparity in diabetes care due to age, gender, race/ethnicity, and psychiatric diagnosis. However, married status was associated with a higher likelihood of receiving all three diabetic services (34% vs. 17%, p=0.002). Patients receiving outpatient mental health services from a private physician were more likely to have lipids testing (24% vs. 9% of patients, p<0.001) and eye exams (24% vs. 15%, p=0.028). Extra effort is needed to ensure that patients in public mental health clinics receive recommended diabetes care.