Hyperglycemia, which is often a prelude to diabetes, is common in patients taking the antipsychotic drug clozapine, according to Michael Sernyak, associate professor of psychiatry at Yale School of Medicine.
In an article published in the May issue of the Journal of Clinical Psychiatry, Sernyak said 23 percent of 121 patients who were not previously diagnosed as diabetic and who were taking clozapine had elevated sugar when administered a fasting plasma glucose test. The patients were at Veterans Administration medical centers throughout New England.
Clozapine is what is known as an atypical antipsychotic drug because it is associated with fewer of the side effects like stiffness, restlessness and symptoms mimicking Parkinson's disease than the previous medications like chlorpromazine or haloperidol. However, there have been several reports of hyperglycemia and diabetes associated with clozapine use.
"Given this proportion of positive findings, we suggest that patients receiving clozapine should be considered a group at high risk to develop diabetes mellitus and that they deserve both close monitoring and early intervention at the first sign of the onset of either diabetes or impaired glucose tolerance," Sernyak said.
He said the study was not designed to reach any conclusion concerning the causes of diabetes or hyperglycemia or their overall incidence in patients receiving clozapine. The researchers were interested in how often hyperglycemia or diabetes goes undiagnosed in this particular population.
The American Diabetes Association estimates 50 percent of patients with Type II diabetes are undiagnosed. The outcomes for patients who remain undiagnosed are worse than for patients who are aware of the condition and are taking steps to treat it.
"We expected the ratio to be worse with our patients because they frequently do not receive medical care," Sernyak said.
One concern, he said, is how patients with schizophrenia can manage two serious, chronic illnesses, even just in terms of the number of doctor appointments involved in treating both conditions.
"That's what we're trying to figure out now," he said.
Co-authors included Barbara Gulanski, M.D., assistant professor of internal medicine, endocrinology; Douglas Leslie, assistant professor of psychiatry and in the Department of Epidemiology and Public Health (EPH), and Robert Rosenheck, M.D., professor of psychiatry and in EPH.
The research was supported by the Department of Veterans Affairs.
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