Subthreshold Change in Glycated Hemoglobin and Body Mass Index After the Initiation of Second-Generation Antipsychotics Among Patients With Schizophrenia or Bipolar Disorder: A Nationwide Prospective Cohort Study in Japan

Objective: The risk of diabetes development has been reported to differ among second-generation antipsychotics (SGAs). However, few studies have focused on the subthreshold change in glycated hemoglobin (HbA(1c)). Therefore, this study examined the subthreshold change in HbA(1c) and change in body mass index (BMI) 3 months after patients initiated one of 6 SGAs widely prescribed in Japan. Methods: This is a prospective cohort study of patients followed up based on the Japanese blood glucose monitoring guidelines for patients with schizophrenia. We collected eligible patients' demographic data, medication history, blood tests, and weight measurements both at baseline and 3 months after recruitment, between April 2013 and March 2015. In the 378 patients with schizophrenia, schizoaffective disorder, and bipolar disorder based on ICD-10, we compared the subthreshold change in HbA(1c) and the change in BMI 3 months after antipsychotic initiation by using multivariate regression analysis. Results: The subthreshold change in HbA(1c) 3 months after initiating blonanserin was significantly lower compared with olanzapine (B = -0.17, 95% CI = -0.31 to -0.04). In addition, the change in BMI 3 months after initiating blonanserin and aripiprazole was significantly lower compared with olanzapine (B = -0.93, 95% CI = -1.74 to -0.12; B = -0.71, 95% CI = -1.30 to -0.12, respectively). Conclusions: This is the first study to clarify the differences in the subthreshold change in HbA(1c) among SGAs. Our results suggest that blonanserin is likely to be a favorable treatment for patients with high risk of diabetes.