Effects of risperidone on glucose metabolism in Chinese patients with schizophrenia: A prospective study

Background: While most of the second generation antipsychotic agents are associated with abnormal glucose metabolism, previous studies have shown that risperidone has relatively little effect upon blood glucose levels. This study aimed to explore the effect of risperidone on the glucose-regulating mechanism of patients with schizophrenia by using the oral glucose tolerance test (OGTT), measuring insulin and C-peptide levels. Methods: Thirty inpatients with schizophrenia taking risperidone were studied. All the patients were given a simplified OGTT at baseline and six weeks after treatment. Plasma glucose, insulin, and C-peptide concentrations were measured at fasting, then I and 2 h after OGTT respectively. Other data, including demographic characteristics and plasma drug concentrations, were also recorded. Results: (1) There was no significant increase in the proportion of patients demonstrating abnormal plasma glucose levels compared with baseline (p = 1.000, McNemar test); (2) risperidone was associated with elevated insulin concentrations (p = 0.013), C-peptide levels (p = 0.020), insulin/glucose ratio (p = 0.020) and BM I (p < 0.01); (3) no sex differences in glucose-related measures were observed. Conclusion: Risperidone treatment may be associated with alterations in glucose-regulating mechanisms in patients with schizophrenia. (C) 2008 Elsevier Ltd. All rights reserved.