This is a 12-week, randomized, double-blinded, placebo-controlled trial of telmisartan 80 mg/day as an adjunctive to clozapine or olanzapine therapy, in 70 schizophrenia subjects to examine telmisartan's effect on glucose metabolism, weight, food intake, resting energy expenditure, and body composition. In addition, the study will examine insulin's effects on psychopathology and cognition.

Potential subjects will be identified by their clinicians at the Freedom Trail Clinic, or Massachusetts General Hospital. Approximately 70 subjects will be enrolled.

The specific aims include:

Primary Aims:

1. Examine the efficacy of telmisartan added to regular doses of clozapine or olanzapine in improving insulin resistance.
2. Examine the efficacy of telmisartan in reducing fasting triglycerides.

Secondary Aims:

1. Examine the effects of telmisartan on negative symptoms, positive symptoms, and cognitive function.
2. Examine telmisartan's effects on lipids, body composition, and waist/hip ratio.
3. Examine telmisartan's effects on inflammatory biomarkers including C-reactive protein (CRP) and interleukin 6 (IL-6).

Inclusion Criteria:

1. Age 18-65 years
2. Diagnosis of schizophrenia, any subtype or schizoaffective disorder, any subtype
3. Treatment with clozapine or olanzapine for at least 6 months
4. Stable dose of antipsychotic agent for at least one month
5. Well establish compliance with out-patient medications
6. Females subjects will be eligible to participate in the study if they are of non-childbearing potential or of child-bearing potential and willing to practice appropriate birth control methods (complete abstinence from sexual intercourse, female sterilization, sterilization of male partner, implants of levonorgestrel, injectable progestogen, oral contraceptives, intrauterine devices, or double barrier methods of contraception using spermicide with either a condom or diaphragm) during the study.

Exclusion Criteria:

1. Inability to provide informed consent
2. Current substance abuse
3. Psychiatrically unstable
4. Significant medical illness including severe cardiovascular, hepatic, renal disease
5. Current insulin treatment of diabetes
6. History of immunosuppression
7. Current or recent radiation or chemotherapy treatment for cancer
8. Chronic use of steroids
9. Pregnancy or breast feeding
10. Use of diuretics, digoxin, warfarin because the possible drug-drug interaction of telmisartan