Aims/hypothesis  

Atypical antipsychotic drugs may be associated with obesity and other components of the metabolic syndrome, but this relationship is controversial. We investigated the hypothesis that atypical antipsychotics are associated with a greater degree of metabolic dysfunction than typical agents.

Methods  

Metabolic parameters were measured in 103 diagnostically heterogeneous psychiatric out-patients. Patients had been taking typical or atypical antipsychotic drugs for a minimum of six months.

Results  

Sixty-nine patients were taking atypical agents, 20 typical agents and 14 a combination. Mean values (±SD) for the whole group were: age 43.8 years (11.4); BMI 29.1 kg/m² (5.1); W:H ratio 0.88 (0.09). Metabolic parameters, including beta cell function and insulin sensitivity, measured by HOMA, did not differ with regard to the prescribed antipsychotic drug. Six patients had undiagnosed diabetes, six patients had impaired fasting glucose, and eight fulfilled criteria for the metabolic syndrome, all of whom were taking atypical agents (p=0.07 vs typical agents). Subgroup analyses of those taking atypical agents revealed differences in BMI (mean, ±SD) between olanzapine (27.3 kg/m²±5.1) and quetiapine (31.9 kg/m²±5.1), p=0.01, and HbA_1c (olanzapine, 5.1%±0.6 vs quetiapine, 5.6%±0.6; p=0.03). Other atypical agents were intermediate with regard to these parameters.

Conclusions  

Obesity, dyslipidaemia and abnormalities of glucose homeostasis are prevalent in this group. Patients taking atypical agents showed a trend towards abnormalities of glucose homeostasis. Prospective studies are needed to explore the precise relationship between antipsychotic drugs, glucose homeostasis, obesity and the metabolic syndrome.