Schizophrenia is associated with increased rates of obesity, hyperglycemia, dyslipidemia and type 2 diabetes mellitus, causing increased morbidity and mortality due to acute (e.g., diabetic ketoacidosis) and long-term (e.g., vascular disease) complications. The association of type 2 diabetes and hyperglycemia with schizophrenia was first noted prior to the introduction of antipsychotic medications. However, additional glucoregulatory abnormalities, dyslipidemia, and increased adiposity have all been associated with antipsychotics. Risperidone and olanzapine are the most prescribed antipsychotics for schizophrenia in the U.S. In addition, schizophrenia patients in clinical practice are commonly treated with multi-class polypharmacy, with 35% of atypical antipsychotic prescriptions accompanied by co-prescription of valproate. This combination continues to increase in popularity, despite reports that the addition of valproate may further disturb glucose and lipid metabolism and weight regulation. While sensitive and validated measures of glucose and lipid metabolism and weight regulation are available, very few studies have addressed the metabolic consequences of this common type of polypharmacy.