The 3-Year Clinical and Functional Course of Schizophrenia Among Individuals With and Without Diabetes at Study Entry

Objective: This prospective observational study compared the 3-year clinical and functional course of schizophrenia among individuals with and without diabetes at study entry.

Method: Data were drawn from a large, 3-year, multisite, prospective, naturalistic study of treatment for schizophrenia-related disorders. The study was conducted in the United States between July 1997 and September 2003 and represented treatment practices in diverse systems of care. Participants were diagnosed with schizophrenia or schizoaffective or schizophreniform disorders based on DSM-IV criteria. Clinical and functional outcomes were assessed at study enrollment and at 12-month intervals using standard psychiatric measures, medical records, and a validated patient-reported questionnaire. Diabetes status was determined by participant interview at enrollment. Statistical analyses used mixed models with repeated measures.

Results: Of 594 participants queried about comorbid medical conditions at enrollment, 76 (12.8%) reported having diabetes. Other comorbid conditions were reported by 79% of the diabetes group (N = 60) and 50% of the nondiabetes group (N = 259). Across the 3-year study, participants with diabetes differed significantly from participants without diabetes on 2 of 36 outcome measures: more contacts with nonpsychiatrist physicians (p < .001) and poorer physical health (p = .015). Groups did not differ significantly on mental health symptomatology, mental health resource utilization, legal and safety issues, substance use, productivity, activities and relationships, or quality of life.

Conclusions: In this 3-year, prospective, naturalistic study, the course of schizophrenia did not differ significantly between participants with and without diabetes, although persons with diabetes did have poorer physical health and more contacts with nonpsychiatrist physicians. Findings highlight the need for better medical treatment for people with schizophrenia, both with and without comorbid diabetes.