Neuroleptic drugs diabetes mellitus

Acetazolamide is a carbonic anhydrase inhibitor that reduces aqueous humour production and is therefore indicated in glaucoma to reduce the intraocular pressure. Salbutamol is a selective, short-acting beta2-agonist used as a bronchodilator in asthma. Tolbutamide is a short-acting sulphonylurea used in type 2 (non-insulin dependent) diabetes mellitus. Chlorpromazine is an aliphatic neuroleptic antipsychotic drug used in schizophrenia. Zafirlukast is a leukotriene-receptor antagonist that is indicated in the prophylaxis of asthma but should not be used to relieve acute severe asthma. 

Diabetes was also more common in 63 patients taking clozapine than in 67 receiving typical depot neuroleptic drugs (299). The percentages of type 2 diabetes mellitus were 12% and 6% respectively. Nevertheless, the mechanism is not known. In six patients with schizophrenia, clozapine increased mean concentrations of blood glucose, insulin, and C peptide (300). The authors concluded that the glucose intolerance was due to increased insulin resistance. 

Several cases of de novo onset or exacerbation of existing diabetes mellitus in patients treated with neuroleptic drugs have been reported and were not significantly related to weight gain. These included eight patients treated with clozapine (767,768) and two patients treated with olanzapine (768). 

New-onset diabetes mellitus in such patients is of particular concern, owing to the associated cardiovascular morbidity and the difficulty in managing diabetes in psychiatric patients. Soon after the first neuroleptic drugs were used, associations with weight gain and diabetes were reported (769,770). Nevertheless, even before antipsychotic drugs appeared, diabetes was observed to be more common in patients with schizophrenia (771). The rate of diabetes in patients with schizophrenia has been estimated at 6.2-8.7% (772) and at 0.8% in the general population in the USA (773). 

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