(Ivanhoe Newswire) -- Schizophrenics treated with clozapine and olanzapine may be at an increased risk for developing type 2 diabetes, according to a recent study. Patients taking these antipsychotic agents resisted insulin and had impairment of glucose effectiveness compared with patients taking another drug under study.

Researchers from Massachusetts General Hospital and Harvard Medical School in Boston evaluated 36 non-obese people with schizophrenia or schizoaffective disorder who were treated with clozapine (Clozaril), olanzapine (Zyprexa, Zydis), or risperidone (Risperdal). Participants followed a certain diet to maintain body weight and fasted before having a glucose tolerance test.

Newer, "atypical," antipsychotic agents such as clozapine and olanzapine have been recently linked to several forms of morbidity, according to researchers, including obesity, hyperlipidemia and diabetes. Schizophrenics have a much shorter life expectancy than the general population attributable to many factors, including cardiovascular disease.

Researchers conclude, "Psychiatrists and primary care professionals should be aware that patients treated with clozapine and olanzapine may be at increased risk for insulin resistance, even if not obese. Patients treated with these agents should be routinely screened, counseled to reduce risk, and provided early interventions."