Differential effects of antipsychotic agents on the risk of development of type 2 diabetes mellitus in patients with mood disorders

Background: Atypical antipsychotics are being used increasingly in the management of mood disorders. Objective: The objective of this study was to investigate the association between exposure to antipsychotic therapy and newly reported type 2 diabetes mellitus in patients with mood disorders. Methods: Claims data for the period January 1996 through December 1997 were analyzed for patients with mood disorders in 2 large US health plans. Logistic regression models were used to determine the odds of reporting diabetes in patients exposed to risperidone, olanzapine, or high- or low-potency conventional antipsychotics compared with untreated patients, taking into account duration of treatment and dosage. Some of the covariates used in the models were concurrent use of antipsychotics, use of other psychotropic drugs, age, sex, and length of observation. Results: Based on the claims data, 849 patients were exposed to risperidone, 656 to olanzapine, 785 to high-potency conventional antipsychotics, and 302 to low-potency conventional antipsychotics; 2644 patients were untreated. The odds of newly reported type 2 diabetes in patients who received risperidone were not significantly different from those in untreated patients (12-month odds ratio [OR] = 1.024; 95% CI, 0.351–3.015). The odds in patients treated with high-potency conventional antipsychotics also did not differ significantly from those of untreated patients (12-month OR = 1.945; 95% CI, 0.794–4.786). Unlike patients who received risperidone or high-potency conventional antipsychotics, patients who received olanzapine (12-month OR = 4.289; 95% CI, 2.102–8.827) and low-potency conventional antipsychotics (12-month OR = 4.972; 95% CI, 1.967–12.612) had significantly higher odds for the development of type 2 diabetes compared with untreated patients. Conclusions: These findings suggest that some antipsychotics may increase the risk for the development of type 2 diabetes in patients with mood disorders and that the effect may vary by drug. In contrast to olanzapine and low-potency conventional antipsychotics, risperidone and high-potency conventional antipsychotics were not associated with an increased risk for development of type 2 diabetes in this patient population.