Brief Communication Diabetes Mellitus and Impaired Glucose Tolerance in Patients With Schizophrenia

Compared with the general population, it has been shownthat patients with schizophrenia have a higher risk of im-paired glucose tolerance and diabetes mellitus (DM) (1). A study of 248 patients conducted in Japan reported a type 2 DM prevalence of 8.8%, compared with 5 % in a control group matched for age and sex (2). Another study by Mukherjee and others reported an overall prevalence of 15.8 % among schizo-phrenia patients in Italy (3), which is considerably higher than reports from population surveys in Italy. A recent study by Dixon and others, using databases collected by the Schizo-phrenia Patient Outcomes Research Team (PORT), found that rates of diagnosed diabetes (14.9%) exceeded general popula-tion statistics well before the widespread use of the newer antipsychotic drugs (4). Several factors may contribute to schizophrenia patients ’ in-creased susceptibility to developing DM. For example, poor health behaviours are likely to be an important contributing factor. Brown and others evaluated 102 schizophrenia Can J Psychiatry, Vol 48, No 5, June 2003 345 Objectives: This study aimed to establish the prevalence of diabetes mellitus (DM) and impaired glucose tolerance in patients with schizophrenia and to elucidate some of the fac-tors associated with hyperglycemia. Methods: We studied a sample of 194 patients with schizophrenia. We determined fasting blood glucose and insulin levels at the start of the testing period; patients were given an oral glucose tolerance test after an overnight fast. Results: The overall prevalence of diabetes and impaired glucose tolerance in these pa-tients was 16.0 % and 30.9%, respectively. These rates were higher than those reported in the general population. Patients with disordered glucose homeostasis were significantly older (P = 0.005, Kruskal–Wallis test). There was no significant effect of sex or ethnicity on diabetes. Conclusions: Our findings suggest that patients with schizophrenia are more vulnerable to developing DM. We caution clinicians to be mindful of the increased risk and to be vigilant for such a development