Atypical antipsychotic agents and increased risk of diabetes: class action or differential action?

Atypical antipsychotic (AAP) agents are useful in treating patients with schizophrenia and other psychosis. Their advantages are the low incidence of extrapyramidal side effects, and possible amelioration of negative, cognitive and mood symptoms. Occurrence of diabetes after AAP drug administration is of concern as patients do not often recognise their symptoms, physicians may fail to diagnose early, with consequent morbidity and mortality. The symptoms of psychosis, including lack of insight and motivation, may decrease the ability of schizophrenic patients to communicate potential health problems. Whether or not AAP drugs induce diabetes and, if they do, if it is a class action or a differential action, is often debated. Clinical evidence on AAP drug-induced diabetes is mounting. With their discontinuation, the diabetes often dissipates, but reappears when they are started again, thereby implicating the AAP drugs in the development of diabetes. There is still dispute regarding the differential effect of the various AAP drugs in their ability to produce diabetes. Although not scientifically proven, available evidence seems to indicate that clozapine and olanzapine may have a higher propensity to induce diabetes compared with other AAP drugs.