PURPOSE: The incidence of type 2 diabetes in children and adolescents has been reported to increase recently. The aim of this study is to investigate the clinical features of type 2 diabetes developing during childhood and adolescent period. METHODS: The medical records of 33 patients with type 2 diabetes were reviewed. We analysed clinical manifestations, demographic data, and modes and responses of treatment. RESULTS: Age at diagnosis was 13.4+/-1.8 years. Seventy percent of patients revealed pubertal signs at diagnosis. Half of the patients had BMI more than 25 kg/m2. Seventy-three percent of patients had family history of type 2 diabetes. Acanthosis nigricans were found in 18% of patients. Nineteen(57.6%) patients were diagnosed incidentally by random urine or blood glucose test without any typical diabetic symptom or sign. The modes of therapy to control hyperglycemia were insulin alone(75.8%), oral hypoglycemic agents alone(9.1%), insulin and oral hypoglycemia agents(9.1%), and only diet with exercise(6%). At the time of investigation, 45.5% of patients were not using insulin. The typical diabetic symptoms at diagnosis were more prevalent in patients who required insulin for more than two years than patients who did not(P<0.05). CONCLUSION: The development of type 2 diabetes in children and adolescents is possibly related to puberty, obesity, family history, and defects in insulin secretion rather than insulin resistance. Many children and adolescents with type 2 diabetes required insulin initially and some of them could discontinue. More than half of the patients were diagnosed as diabetes without any typical symptom or sign, which might be one of the predictive factors of the prolonged insulin requirement.