Background and objectives: Atypical antipsychotics have been related with hyperglycaemia, diabetes mellitus, weight gain and lipid alterations in some patients. This study analyzed whether continuous treatment with risperidone, olanzapine, or clozapine entails a risk of glucose or lipid metabolism alterations in schizophrenic patients.
Patients and method: Patients included in this study were schizophrenics who had received mono-therapeutic with clozapine, olanzapine or risperidone for a period of 1 to 3 years. Those schizophrenic patients who were diagnosed as diabetic during psychiatric treatment and those who showed fasting glycemia greater than or equal to 126 mg/dl in two consecutive measurements were considered cases. The remaining schizophrenic patients who were receiving treatment and did not show these alterations were considered controls.
Results: In the adjusted analysis (multivariate logistic regression) of the effect of antipsychotic treatment on the presence of diabetes, which also assessed age and body-mass index, the adjusted odds ratio (OR) for olanzapine relative to risperidone was 2.22 (95% confidence interval [CI], 1.12-4.22), (p = 0.0228); and that for clozapine relative to risperidone was 2.87 (95% CI, 1.19, 6.93), (p = 0.0192). Both results reveal a significantly greater risk for the appearance of diabetes mellitus in patients treated with olanzapine or clozapine than in those treated with risperidone. There were significant differences in the risk of increase in triglycerides in patients receiving olanzapine (OR = 1.34; p = 0.0075) and clozapine (OR = 1.58; p = 0.0028).
Conclusions: The risk of the appearance of diabetes mellitus in patients treated with olanzapine is twice as high as that in patients treated with risperidone, and the risk in patients treated with clozapine is nearly triple as high as that found in patients treated with risperidone. Risperidone appears to be a safer antipsychotic drug in the long term, with regard to the risk of alterations in glucose and lipid metabolism.