Weight gain and new onset diabetes associated with olanzapine and risperidone

To assess whether newer antipsychotic medications are associated with weight gain and development of diabetes.

Retrospective cohort study.

Data from a comprehensive electronic medical record serving an urban public hospital and a citywide network of mental health clinics.

Three thousand one hundred fifteen patients at least 18 years old who were prescribed a single antipsychotic drug for at least 1 year.

We identified independent predictors of significant weight gain (> or =7%) and new onset of diabetes mellitus in the first year of antipsychotic drug treatment, using logistic regression adjusted for demographic characteristics, obesity, preexisting psychiatric diagnoses, alcohol and drug abuse, number of primary care, psychiatric clinic, and emergency department visits, and pretreatment weight.

Twenty-five percent of patients taking older phenothiazines developed significant weight gain in the first year of treatment compared to 40% of the patients taking olanzapine (adjusted odds ratio [OR], 2.8; 95% confidence interval [CI], 1.7 to 4.6; P <.0001) and 37% of patients taking risperidone (adjusted OR, 2.3; 95% CI, 1.5 to 3.4; P <.0001). New diabetes developed in 3% of patients taking older phenothiazines was new onset diabetes compared to 8.0% of patients taking olanzapine (adjusted OR, 1.9; 95% CI, 1.1 to 3.3; P=.03) and 3.5% of patients taking risperidone (adjusted OR, 0.7; 95% CI, 0.4 to 1.4; P=.3). No association was found between significant weight gain and developing diabetes (adjusted OR, 0.7; 95% CI, 0.4 to 1.4; P=.4).

Olanzapine and risperidone use was associated with gaining weight in the first year, but only olanzapine was associated with developing diabetes mellitus.