Rapid-onset clozapine-induced loss of glycaemic control: case report

Clozapine has proved to be an effective antipsychotic for the treatment of refractory schizophrenia – characterised by the persistence of symptoms despite optimal treatment trials with at least two different antipsychotics at adequate dose and duration – but its use is hampered by adverse effects. The development of clozapine-induced diabetes is commonly considered to arise as part of a metabolic syndrome, associated with weight gain, and thus evolves slowly. We present the case of an individual with refractory schizophrenia and metformin-controlled diabetes who developed rapid-onset insulin-dependent hyperglycaemia immediately after starting clozapine. Given the refractory nature of his illness, the decision was made to continue clozapine and manage the diabetes. This case supports the existence of a more direct mechanism by which clozapine alters glycaemic control, aside from the more routine slow development of a metabolic syndrome. DECLARATION OF INTEREST: S.S.S. is supported by a European Research Council Consolidator Award (Grant Number 311686) and the National Institute for Health Research (NIHR) Mental Health Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London. The funders had no role in study design, data collection, data analysis, data interpretation or writing of the report. COPYRIGHT AND USAGE: © The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.