Hyperglycemia and Diabetes in Patients With Schizophrenia or Schizoaffective Disorders

Abstract

OBJECTIVE—Pharmacoepidemiological studies have shown an increased prevalence of diabetes in patients with schizophrenia. To address this issue, we decided to assess glucose metabolism in a population of patients with schizophrenia or schizoaffective disorder. RESEARCH DESIGN AND METHODS—Oral glucose tolerance tests (OGTTs) were performed in 200 unselected in- and outpatients. Insulin sensitivity and β-cell function were assessed using the homeostasis model assessment (HOMA) indexes and 30-min glucose and insulin levels. RESULTS—The mainly Western European (87.7%) study population had a mean age of 40.8 years, was 70% male, and had a mean fasting glucose of 5.1 mmol/l and a mean fasting insulin of 14.8 mU/l. Hyperglycemia was present in 7% of the population: 1.5% with impaired fasting glucose and 5.5% with impaired glucose tolerance. The prevalence of diabetes was 14.5%, of which 8% was previously known and 6.5% was newly diagnosed. Compared with a 1.5% prevalence of diabetes in the age-matched general Dutch population, the prevalence of identified cases was significantly increased in the study population. Comparable figures on the prevalence of hyperglycemia in the general population are not available. Insulin resistance was increased in the study population as a whole (HOMA of insulin resistance: 3.1–3.5), irrespective of the use of antipsychotic medication and, if used, irrespective of its type (typical or atypical). No indication of β-cell defect was found, whereas a nonsignificant increased insulin resistance was found with antipsychotic medication. CONCLUSIONS—OGTTs in 200 mainly Caucasian patients with schizophrenia or schizoaffective disorder, mean age 41 years, showed that 7% suffered from hyperglycemia and 14.5% from diabetes. The prevalence of diabetes was significantly increased compared with the general population. No differential effect of antipsychotic monotherapy in diabetogenic effects was found. Therefore, a modification of the consensus statement on antipsychotic drugs, obesity, and diabetes is proposed, i.e., measurement of fasting glucose in all patients with schizophrenia, irrespective of prescribed antipsychotic drug.