The increased risk of diabetes mellitus in adult patients treated with second generation antipsychotics is a topic that has been vigorously debated in recent years. However, a literature search indicates that only very limited information is available about the use and the potential metabolic risks of antipsychotics in children and adolescents. We present and discuss a case study in which severe glucose abnormalities were detected in a 14-year-old, non-psychotic patient who was being treated with risperidone. The glucose abnormalities were found to be reversible when risperidone was discontinued. The case-study highlights the importance of screening for and detection of metabolic abnormalities in children and adolescents who are being treated with second generation antipsychotics. It is particularly important that children with additional risk factors are closely monitored.