Rapidly developing hyperglycemia during treatment with olanzapine.

OBJECTIVE

To report a case of rapidly occurring hyperglycemia that occurred in a geriatric patient 3 days after treatment with olanzapine.

CASE SUMMARY

An 89-year-old man was admitted for dementia with behavioral disturbance and psychosis and was started on olanzapine 2.5 mg twice daily. Due to paranoia and agitation, the dose was increased to 5 mg twice daily after 2 days. Subsequently, he developed hyperglycemia (fasting blood glucose 138 mg/dL) that resolved when olanzapine was stopped and recurred (fasting blood glucose 150 mg/dL) after 2 days of rechallenge with olanzapine 2.5 mg twice daily. In addition, his overall medical status worsened, as he developed concurrent acute renal failure and became more confused and lethargic. The hyperglycemia once again resolved with discontinuation of the drug.

DISCUSSION

We postulate that the rapid onset of hyperglycemia and the resulting medical sequelae were due to olanzapine. An objective causality assessment revealed that the adverse drug event was probable. There have been numerous case reports of hyperglycemia with olanzapine in the literature, but none reported hyperglycemia within days of initiation of the medication. Although weight gain often coincides with hyperglycemia in patients taking atypical antipsychotics, it does not seem to be a necessary causal factor. Recent data in animal studies have indicated that olanzapine and clozapine rapidly impair whole-body insulin sensitivity in a dose-dependent manner.

CONCLUSIONS

Clinicians treating elderly patients with olanzapine should be aware of the potential for rapidly developing hyperglycemia and monitor such patients accordingly.