Undiagnosed Hyperglycemia in Patients Treated With Atypical Antipsychotics

Background: The use of atypical antipsychotics has been associated with abnormalities of glucose metabolism in patients with schizophrenia. This study was designed to determine the proportion of undiagnosed hyperglycemia in patients receiving a broad range of atypical antipsychotics.

Method: All outpatients treated at an urban Veterans Affairs medical center who received a prescription for clozapine, risperidone, olanzapine, quetiapine, or ziprasidone were identified, and an attempt was made to obtain a fasting plasma glucose (FPG) test. Testing took place October 2000 to November 2002. Patients previously diagnosed as diabetic were excluded.

Results: Of the 647 patients who received antipsychotic prescriptions and were not diagnosed as diabetic, 494 (76.4%) had a random glucose result, while 153 (23.6%) had an FPG result. Within the FPG group, 107 (69.9%) had a normal FPG level, while 46 (30.1%) had an abnormally elevated FPG. There were no differences between these 2 groups in terms of race/ethnicity, age, body mass index, or comorbid diagnoses. However, significantly more patients receiving clozapine were found to have occult hyperglycemia (p = .001); no significant differences in the percentage of patients with FPG levels > = 100 mg/dL and those with FPG levels < 100 mg/dL were observed for any of the other medications.

Conclusion: Hyperglycemia is common in patients treated with atypical antipsychotics and thought to be euglycemic. Screening for elevated FPG is indicated for patients receiving atypical antipsychotics.