OBJECTIVES: Use of conventional and atypical antipsychotics in persons with schizophrenia has been associated with increased risk of developing type 2 diabetes. We studied the potential link between comorbid diabetes and functional status in persons with schizophrenia. METHODS: In June 2002, 850 people with schizophrenia, identified through the National Alliance for the Mentally Ill and community mental health centers, completed self-administered questionnaires. Of these, 109 (12.8%) respondents had diabetes. Subjects were asked how many hours per week they typically engaged in paid employment, volunteer work, or school/college work. Those who participated in at least one of these activities were considered to engage in productive activity. Gender, age, and race were controlled using multiple regression analysis for hours per week of productive activity and logistic regression for participation in productive activity. RESULTS: Compared with those with diabetes, respondents without diabetes were 1.97 (P=0.002) times as likely to participate in productive activities. Paid employment was 2.57 (P<0.001) times more likely; volunteer work, 1.56 (P=0.073) times more likely; and school/college work, 7.32 (P<0.001) times more likely. Respondents without diabetes averaged 12.41 (P<0.001) more hours per week of productive activity than those with diabetes. CONCLUSION: Among people with schizophrenia, comorbid diabetes has a negative impact on functioning as measured by engagement in productive activities.