Some atypical antipsychotic drugs, especially olanzapine (Zyprexa medication, Eli Lilly) and clozapine (Clozaril®, Novartis), may induce glucoregulatory dysfunction that can lead to diabetes. Researchers who analyzed data on 5,837 patients in the Veterans Affairs database found that olanzapine therapy was associated with a 37% higher risk of diabetes compared with risperidone treatment.
Of 5,837 patients, 368 (6.3%) had a marker for diabetes, on average within 15 months. Only generic olanzapine was associated with the increased risk, which was consistent across all analyses, including those that controlled for factors such as other drugs, race, age, and substance abuse.
The researchers note that their numbers might be low, because the markers they used (i.e., the International Classification of Disease ICD-9-CM diagnosis codes and prescriptions for hypo-glycemic drugs) tend to underestimate the prevalence of new-onset diabetes.