The prevalence and clinical-demographic correlates of diabetes mellitus in chronic schizophrenic patients receiving clozapine

Hum Psychopharmacol. 2011 Aug;26(6):392-6. doi: 10.1002/hup.1220. Epub 2011 Aug 8.


Objective: To examine the prevalence and correlates of diabetes in a large sample of Chinese patients with schizophrenia on long-term clozapine treatment, because this population previously has received little systematic study.

Methods: Two hundred and six inpatients meeting Diagnostic and Statistical Manual of Mental Disorders, 4th Edition schizophrenia criteria were recruited in a cross-sectional naturalistic study, and compared with 615 healthy control subjects matched for age, sex, education, and body mass index (BMI). The patient's psychopathology was assessed using the Positive and Negative Syndrome Scale (PANSS). Diagnoses of diabetes were established through review of medical records and fasting blood glucose testing, or an oral glucose tolerance test.

Results: Diabetes mellitus was more common in patients than in the normal controls (22.3% vs 6.2%) (odds ratio = 4.37, confidence interval (CI) 2.76-6.92, p < 0.001). The prevalence of diabetes increased with age across five age-groups as compared with normal controls (X(2) = 18.0, df = 4, p = 0.001). The PANSS total score and sub-scores showed no differences between the diabetic and non-diabetic groups. Logistic regression in the patients revealed significant associations between diabetes and a family history of diabetes (p < 0.001), age (p < 0.01), and BMI (p < 0.05).

Conclusion: Long-term clozapine treatment was associated with an increased and clinically important risk of diabetes mellitus in Chinese chronic schizophrenic patients, which is consistent with previous reports in Western populations.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Age Factors
  • Aged
  • Antipsychotic Agents / adverse effects*
  • Antipsychotic Agents / therapeutic use
  • Blood Glucose
  • Body Mass Index
  • China / epidemiology
  • Chronic Disease
  • Clozapine / adverse effects*
  • Clozapine / therapeutic use
  • Cross-Sectional Studies
  • Diabetes Mellitus / chemically induced
  • Diabetes Mellitus / epidemiology*
  • Female
  • Glucose Tolerance Test
  • Humans
  • Logistic Models
  • Male
  • Middle Aged
  • Prevalence
  • Psychiatric Status Rating Scales
  • Risk Factors
  • Schizophrenia / drug therapy*
  • Schizophrenia / physiopathology


  • Antipsychotic Agents
  • Blood Glucose
  • Clozapine