Up to 1 in 3 of older people with schizophrenia might have undiagnosed diabetes

Researchers linked with the University of Leicester have found high rates of diabetes in schizophrenia which is often overlooked.

Rates of diabetes are at least twice as high in those with severe mental illness (SMI) such as schizophrenia and bipolar disorder as those in the general population but it remains challenging to identify. In this, the largest study of screening for diabetes in patients with severe mental illness, researchers found 10% of such patients had diabetes but rates increased dramatically with age to 29% in women aged 55 to 64 years and 32% of men aged 55 to 64 years. Further, usual clinical and biochemical tests were not sufficient and failed to identify the majority of patients. Only when tests were combined, did the accuracy meet adequate standards. 

Professor Alex Mitchell, Honorary Professor of Psycho-oncology and Liaison Psychiatry in the University’s Leicester Cancer Research Centre, who led the study commented: "This is the first large scale study to examine diabetes and SMI across the age spectrum. Diabetes and pre-diabetes increased markedly with age perhaps because of the length of time risk factors remain unidentified. After the age of 45 years more than half of patients had diabetes or prediabetes. By the age of 55 years, 1 in 3 had developed frank diabetes. Further, we found that the usual test for diabetes (HBA1c) only correctly identified diabetes in 19% of people with severe mental illness. Clinical symptoms and signs were similarly inaccurate. We recommend doctors should regularly look for diabetes in patients with severe mental illness taking long-term medication but they will have to rely on more than one single test."

The paper ‘Which clinical and biochemical predictors should be used to screen for diabetes in patients with serious mental illness receiving antipsychotic medication? A large observational study’ has been published in PLoS One. https://doi.org/10.1371/journal.pone.0210674