Type 2 diabetes mellitus is more prevalent in patients with schizophrenia compared to the general population. However, there is a lack of evidence that co-morbidity with this and/or other physical diseases lead to excess mortality in schizophrenia. We investigated whether diabetes and other diseases are increased and are predictors of mortality in schizophrenia.

During 2000-2007, 679 patients with schizophrenia were admitted to University Hospital Birmingham NHS Trust, co-morbidities were compared with 88778 age- and gender group-matched hospital controls. Predictors of mortality were identified using logistic regression.

Type 2 diabetes mellitus was increased in schizophrenia compared to hospital controls (11.3 versus 6.3%). The prevalence of diabetes mellitus at first admission was higher in later deceased patients with schizophrenia (n=100, 24.0%) than those surviving (n=579, 9.2%). Predictors of mortality in schizophrenia were age (relative risk RR=1.1/year), type 2 diabetes mellitus (RR=2.2), pneumonia (RR=2.7), heart failure (RR=2.9) and chronic renal failure (RR=3.2). The impact of diabetes mellitus on mortality was significantly higher in schizophrenia than in hospital controls (RR=2.2 versus RR=1.1), deceased schizophrenics had more often suffered diabetes mellitus than deceased controls (10.5%).

Co-morbidity with diabetes mellitus is increased in schizophrenia in comparison with hospital controls; it also causes significant excess mortality in schizophrenia. Thus, monitoring for and prevention of type 2 diabetes mellitus is of utmost relevance in schizophrenia.