Treatment with antipsychotics and the risk of diabetes in clinical practice.

BACKGROUND: Treatment with antipsychotics seems to increase the risk of developing diabetes but the association is poorly characterised in clinical practice. AIMS: To investigate and characterise the incidence of diabetes for people treated with antipsychotic medication in clinical practice.
METHOD: The study used the linkage of registers of all prescribed antipsychotics, antidiabetics and diagnoses of diabetes in Denmark during a period from 1996 to 2005 and identified all people treated with antipsychotics in Denmark and a random sample of about 30% of the total Danish population.
RESULTS: In total, 345,937 patients who purchased antipsychotics and 1,426,488 unexposed individuals were included in the study. Among the total population, 50,379 individuals subsequently developed incident diabetes. Compared with unexposed individuals, treatment with first- (rate ratio, RR = 1.53, 95% CI 1.49-1.56) as well as second-generation (RR = 1.32, 95% CI 1.22-1.42) antipsychotics was associated with increased risk of subsequent incident diabetes. The rate of incident diabetes varied substantially between individual second-generation antipsychotic drugs (olanzapine, risperidone clozapine compared with unexposed individuals: low to moderate rate ratio between 1.17 and 1.57; ziprasidone and sertindol: two or more times increased rate ratio; amisulpride, quetiapine and aripiprazole: no significantly increased rate ratio). For both first- and second-generation antipsychotics, the incidence of diabetes increased with the number of prescriptions. Additionally, the incidence of diabetes increased with the number of combined antipsychotic drugs.
CONCLUSIONS: In clinical practice, treatment with first- and second-generation antipsychotics is associated with an increased risk of developing incident diabetes with large differences between individual drugs. The risk increases with the duration of treatment and with polypharmacy of antipsychotic drugs.