Q. Does Risperdal cause a higher than normal tendency towards diabetes II? Or if they have a familial tendency, can it push it to occur, via symptoms? I work for home health as the Quality Assessment nurse and have noticed that the doctors have steered towards olanzapine more and more.

In the past I was aware that we were doing blood glucose on the psychiatric pediatric unit I worked on, but when I shared the information about Risperdal no one knew about it. It seems appropriate since a lot of our patients are diabetic as well as dealing with organic or long standing mental illnesses. Can you provide me with more information?

A. The whole question of atypical antipsychotics (AAs) and their effects on glucose regulation remains controversial. The developing consensus, however, is that glucose dysregulation is probably more common with olanzapine and clozapine that with other AAs, such as risperidone. But, glucose dysregulation certainly can occur with risperidone (RSP), as well as with conventional, first-generation neuroleptics. Let's back up for a minute, though.

One complicating factor in this story is the higher-than-normal incidence of diabetes among individuals with schizophrenia--even those not taking antipsychotic medication. Schizophrenic individuals also have higher rates of obesity than the general public, and this, in turn, may contribute to increased risk of diabetes.

In one large, retrospective study of over 33,000 patients [Caro et al, J Clin Psychiatry 2002;63:1135-9], 319 patients developed diabetes on olanzapine treatment, versus 217 taking risperidone. Controlling for age, gender, and haloperidol [Haldol] use, there was a 20% increased risk of diabetes with olanzapine relative to RSP.

Another study (Hedenmalm et al, Drug Saf 2002;25:1107-16) found that clozapine, olanzapine, and RSP were all significantly associated with glucose intolerance, whereas haloperidol was not. Risk factors for glucose intolerance/dysregulation included an underlying diabetic condition; increase in weight; and concomitant use of valoprate or SSRI-type antidepressants (such as Prozac or Paxil).

Other reports note cases of olanzapine-related glucose intolerance that are not associated with weight gain, and which may present as frank diabetic ketoacidosis early in treatment. A family history of diabetes also may increase risk of glucose intolerance, and should be elicited from all patients. Careful baseline and follow-up measures of glucose control are also indicated in patients taking atypical antipsychotics.

October 2003

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