Childhood overweight and obesity related insulin resistance can be evaluated with glycosylated haemoglobin (HbA1c) which would be helpful to prevent the progression from impaired glucose tolerance to Type 2 Diabetes Mellitus (T2DM). This study was aimed to determine the HbA1c level among urban overweight and obese school students in Batticaloa District, Sri Lanka. A cross-sectional descriptive study was conducted among 269 overweight and obese advanced level school children from urban 1AB schools in Batticaloa District. Anthropometric measurements and determinations of HbA1c levels were performed. Information on social and lifestyle variables were obtained using validated pre-tested interviewer administered questionnaires. Statistical analysis was performed with SPSS software version 20. Study consists of 41% males and 59% females. The mean BMI of the participants was 28.98 (± 3.68) Kg/m2. The mean HbA1c of participants was 5.4 (± 0.44). Nearly 20% and 3.3% of the HbA1c were in the pre-diabetes and diabetes category respectively. The mean HbA1c was significantly higher in male and obese compared to their counterparts (p<0.05). ANOVA shows a statistically significant difference in mean HbA1c across the ethnicity [F (2, 267)=10.09, p=0.00]. Simple linear regression model found that participant’s predicted HbA1c level is equal to 4.943+0.017 (BMI). The prevalence of pre-diabetes and diabetes among overweight and obese school children was significantly high and BMI showed a weak positive correlation with HbA1c level. Strategies for weight reduction and promotion of healthy lifestyles are necessary to prevent the onset of T2DM during childhood and adolescence.