A cross-sectional, population-based study was conducted on 1,647 Turkish adolescents to determine the prevalence of obesity, impaired fasting glucose (IFG) and type 2 diabetes mellitus (DM2), and to determine whether the recent increase in DM2 prevalence in some countries is applicable to this population. Information was gathered through a questionnaire. All children were screened with physical examination and fasting plasma glucose. 10.7% of adolescents were overweight (BMI 85-95th percentile) and 3.6% were obese (BMI ≥95th percentile). Mean BMI was 20.25 ± 3.31 kg/m2 with maximum BMI 35.88 kg/m2. No child was diagnosed with DM2; 1.96% had IFG (110-126 mg/dl). No significant relationship was found between IFG and obesity, socio-economic status (SES) or family history of DM. The risk of obesity was increased among children with family history of DM or obesity, and among those who had low physical activity and were of high SES level. This analysis represents the population-based data upon which future studies will be based. © Freund Publishing House Ltd., London.