A prospective study of impairment in glucose control caused by clozapine without changes in insulin resistance

Am J Psychiatry. 2004 Feb;161(2):361-3. doi: 10.1176/appi.ajp.161.2.361.

Abstract

Objective: This prospective study examines the effect of clozapine on glucose control and insulin sensitivity.

Method: Glucose homeostasis was measured in nine female and 11 male patients with schizophrenia (mean age=30.5 years, SD=7.4) before clozapine treatment and after a mean of 2.5 months (SD=0.95) of clozapine treatment. Oral glucose tolerance and insulin levels were measured. Insulin resistance level was measured by the homeostasis model assessment.

Results: Eleven (55%) of the patients developed abnormal glucose control; the mean age of these patients was 30.2 (SD=7.1), and five were women. Patients' insulin resistance at baseline (mean insulin resistance level=3.88, SD=2.93) was unaffected by clozapine. Mean fasting and 2-hour glucose levels significantly increased by 0.55 mmol/liter and 1.4 mmol/liter, respectively. There was no correlation between change in body mass index and change in fasting glucose levels.

Conclusions: Clozapine impairs glucose control within 4 months of treatment, independent of changes in insulin sensitivity and body mass index.

MeSH terms

  • Adult
  • Antipsychotic Agents / adverse effects*
  • Blood Glucose / drug effects*
  • Body Mass Index
  • Clozapine / adverse effects*
  • Female
  • Glucose Tolerance Test
  • Humans
  • Male
  • Metabolic Syndrome / chemically induced*
  • Prospective Studies
  • Schizophrenia / drug therapy*
  • Severity of Illness Index

Substances

  • Antipsychotic Agents
  • Blood Glucose
  • Clozapine