I read with interest Eric Wooltorton's article about trials of risperidone involving patients with dementia1 and would like to clarify an important point. In the article, Wooltorton stated that “Risperidone . . . appears to cause diabetes.” The cause of diabetes mellitus is in fact unknown. Rather, this condition is a multifactorial phenotype, and it is unlikely that any single factor will be sufficient to explain the illness in most populations. An article of which I was a coauthor2 was inappropriately cited as a reference for the suggestion that risperidone causes diabetes mellitus; however, the cited article does not make such a statement.
It is emerging that several of the novel antipsychotics are associated with weight gain. Not only is this effect disquieting for patients, but it may also increase the risk of obesity-related morbidity. Furthermore, some predisposed patients receiving antipsychotic medications may have de novo glucose dysregulation, exacerbation of pre-existing diabetes mellitus or the induction of diabetic ketoacidosis. Although the risk associated with each of the commercially available novel antipsychotics is not definitively known, there have been significantly more cases of these problems with clozapine and olanzapine.3,4,5 However, that being said, it remains inaccurate to say that either of these drugs “causes” diabetes.
Roger S. McIntyre Assistant Professor Department of Psychiatry University of Toronto Toronto, Ont.
Footnotes
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Competing interests: Dr. McIntyre is a paid consultant to Eli Lilly, Janssen, AstraZeneca, Wyeth, and Organon. He has received speaker fees from Eli Lilly, Jannsen Ortho, AstraZeneca, GlaxoSmithKline, Lundbeck, Wyeth, Organon, and ORYX Pharmaceuticals.