The present analytic study was planned to study the impact of overweight and obesity on glucose tolerance in adolescents. Thirty overweight (BMI analogue ≥ 25–29.9 kg/m2) and 30 obese (BMI analogue ≥ 30 kg/m2) adolescents were included as cases and 30 healthy age and sex matched adolescents comprised the control group. All the study participants were subjected to oral glucose tolerance test (OGTT) as a measure of glucose tolerance.Means of fasting blood glucose levels in normal, overweight and obese groups were 84.5 mg/dl, 86.7 mg/dl and 94.8 mg/dl respectively. Means of two hourly blood glucose levels in normal, overweight and obese groups were 105.8 mg/dl, 117 mg/dl and 127.1 mg/dl respectively. Oral Glucose tolerance test (OGTT) was normal in all the participants from control group but was impaired in four overweight adolescents. In obese group, OGTT was impaired in eight subjects and one obese child had fasting and 2 hourly blood glucose levels in diabetic range.