Antipsychotic medications are associated with an increased risk of diabetes. Previous studies have also found an increased risk of type 2 diabetes mellitus in the relatives of schizophrenia probands. The aim of this study was to explore the metabolic adverse effects of olanzapine in a cohort of patients with newly diagnosed psychosis and minimal or no exposure to antipsychotics. Patients with newly diagnosed psychosis (n = 30) were enrolled in a 16-week open trial of olanzapine. Body mass index, fasting glucose, hemoglobin A1c, fasting insulin, IL-6, and a fasting lipid profile were measured at baseline and at 4-week intervals. There was a significant, linear increase over time in fasting glucose (P = 0.043), weight (P < 0.001), body mass index (P < 0.001), total cholesterol (P = 0.005), triglycerides (P = 0.003), and low-density lipoprotein (P = 0.013), but not hemoglobin A1c (P = 0.691), fasting insulin (P = 0.690), IL-6 (P = 0.877), or high-density lipoprotein (P = 0.446). An abnormal baseline IL-6 was a significant predictor of a greater increase in both total cholesterol (P < 0.01) and low-density lipoprotein (P < 0.01). Otherwise, neither parental history of type 2 diabetes mellitus nor baseline IL-6 predicted changes in metabolic measures. Changes in metabolic measures with olanzapine treatment can be detected early in the treatment of patients who are previously antipsychotic naive. The absence of a change in fasting insulin suggests a failure of pancreatic islet cells to compensate for the increase in fasting glucose.
Trial registration: ClinicalTrials.gov NCT00446992.