Assessment of independent effect of olanzapine and risperidone on risk of diabetes among patients with schizophrenia: population based nested case-control study

BMJ 2002; 325 doi: (Published 03 August 2002) Cite this as: BMJ 2002;325:243
  1. Carol E Koro, postgraduate (ckoro001{at},
  2. Donald O Fedder, professorb,
  3. Gilbert J L'Italien, directorf,
  4. SheilaS Weiss, assistant professorb,
  5. LaurenceS Magder, associate professorc,
  6. Julie Kreyenbuhl, assistant professord,
  7. DennisA Revicki, chairman of boardg,
  8. RobertW Buchanan, professore
  1. aPharmaceutical Health Services Research Department, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
  2. bPharmacy Practice and Science, University of Maryland
  3. cEpidemiology and Preventive Medicine, School of Medicine, University of Maryland
  4. dVA Capital Network Mental Illness Research, Education, and Clinical Center, University of Maryland
  5. eMaryland Psychiatric Research Center, University of Maryland
  6. fDecision Sciences Outcomes Research, Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, CT 06492, USA
  7. gCenter for Health Outcomes Research, MEDTAP International, Bethesda, MD 20814, USA
  1. Correspondence to: C E Koro
  • Accepted 28 February 2002


Objective: To quantify the association between olanzapine and diabetes.

Design: Population based nested case-control study.

Setting: United Kingdom based General Practice Research Database comprising 3.5 million patients followed between 1987 and 2000.

Participants: 19 637 patients who had been diagnosed as having and treated for schizophrenia. 451 incident cases of diabetes were matched with 2696 controls.

Main outcome measures: Diagnosis and treatment of diabetes.

Results: Patients taking olanzapine had a significantly increased risk of developing diabetes than non-users of antipsychotics (odds ratio 5.8, 95% confidence interval 2.0 to 16.7) and those taking conventional antipsychotics (4.2, 1.5 to 12.2). Patients taking risperidone had a non-significant increased risk of developing diabetes than non-users of antipsychotics (2.2, 0.9 to 5.2) and those taking conventional antipsychotics (1.6, 0.7 to 3.8).

Conclusion: Olanzapine is associated with a clinically important and significant increased risk of diabetes.


  • Funding Bristol-Myers Squibb provided the data from the General Practice Research Database for this study at no cost and without restriction.

  • Competing interests GJL is an employee of Bristol-Myers Squibb, Pharmaceutical Research Institute.

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