Ziprasidone for Improving Insulin Sensitivity in People With Schizophrenia Who Are at Risk for Diabetes

People with schizophrenia often lead more sedentary lifestyles than people without the disease, and they are frequently treated with antipsychotic medications that cause weight gain. Combined, these factors produce an increased risk for metabolic syndrome, which can lead to heart disease and type 2 diabetes. Characteristics of metabolic syndrome include carrying excess weight around the abdominal region; high blood pressure; high blood sugar levels; high levels of fat in the blood; and low levels of HDL cholesterol. Recent studies have shown that certain atypical antipsychotic drugs are relatively weight-neutral. Switching from a drug that promotes weight gain to a weight-neutral medication, such as ziprasidone, may result in significant weight loss. There is insufficient evidence, however, demonstrating the extent of improvement in insulin sensitivity after switching medications. This study will evaluate the effectiveness of ziprasidone treatment versus treatment with a standard atypical antipsychotic drug in improving insulin sensitivity and reducing excess abdominal fat storage in people with schizophrenia who are at risk for diabetes. Participants in this open label study will currently be undergoing treatment with risperidone or olanzapine at the time of study entry. Upon study entry, they will be randomly assigned to either switch to ziprasidone treatment or remain on their current medications. Both groups will be treated for 26 weeks. Participants will report to the study site for evaluations biweekly until week 10 and then monthly for the duration of the study. The primary outcomes at Week 26 will be: change from baseline in insulin sensitivity, using an intravenous glucose tolerance test; change from baseline in ivisceral fat mass, using a CT scan.