Diabetes mellitus and schizophrenia: historical perspective

Background Although recent research has focused on the possible role of antipsychotic medications in the development of diabetes mellitus, studies conducted in the pre-neuroleptic era suggest that schizophrenia itself might predispose individuals to diabetes. Aims To test the hypothesis that diabetes mellitus is an integral part of schizophrenia. Method Historical literature review. Results Many people with severe mental illnesses, including dementia praecox, showed abnormal responses to insulin and diabetes-like glucose tolerance curves long before the advent of phenothiazines. Early studies with chlorpromazine suggested that a latent tendency towards diabetes in patients with schizophrenia could be unmasked by this treatment. Conclusions Diabetes and disturbed carbohydrate metabolism may be an integral part of schizophrenia. Further research is required to explain how metabolic factors, medications and lifestyle factors might precipitate diabetes in patients with this mental disorder. Declaration of interest D.K. has received lecture fees and educational grants from Eli Lilly, Pfizer,Janssen-Cilag and AstraZeneca.