Improving Diabetes Risk Factors in Persons With Schizophrenia or Bipolar Disorder by Switching to Ziprasidone

Inclusion Criteria: * Diagnosis of schizophrenia or schizoaffective disorder or bipolar disorder * BMI\>29.9 or family history of diabetes and/or abdominal circumference greater than 88 cm in women or 102 cm in men * Pre-diabetic oral glucose tolerance test * Current treatment with olanzapine, risperidone, paliperidone, or quetiapine, or combination of these * Willing to switch to ziprasidone * No psychiatric hospitalizations in past three months and judged by treating clinician to be suitable for antipsychotic medication switch * Able to give informed consent to study Exclusion Criteria: * Judged to be currently suicidal, homicidal, or unable to cooperate with treatment * Unstable serious medical illness * Current use of drugs that interfere with glucose and fat metabolism (sulfonylureas, metformin, thiazolidinediones). The use of "statins" and fibrates will be allowed ONLY if stable dose for past 3 months. * Current diagnosis of diabetes * Fasting blood glucose \>125 mg/dl